Network Working Group J. Wray
Request for Comments: 2744 Iris Associates
Obsoletes: 1509 January 2000
Category: Standards Track
Generic Security Service API Version 2 : C-bindings
Status of this Memo
This document specifies an Internet standards track protocol for the
Internet community, and requests discussion and suggestions for
improvements. Please refer to the current edition of the "Internet
Official Protocol Standards" (STD 1) for the standardization state
and status of this protocol. Distribution of this memo is unlimited.
Copyright Notice
Copyright (C) The Internet Society (2000). All Rights Reserved.
Abstract
This document specifies C language bindings for Version 2, Update 1
of the Generic Security Service Application Program Interface (GSS-
API), which is described at a language-independent conceptual level
in RFC-2743 [GSSAPI]. It obsoletes RFC-1509, making specific
incremental changes in response to implementation experience and
liaison requests. It is intended, therefore, that this memo or a
successor version thereof will become the basis for subsequent
progression of the GSS-API specification on the standards track.
The Generic Security Service Application Programming Interface
provides security services to its callers, and is intended for
implementation atop a variety of underlying cryptographic mechanisms.
Typically, GSS-API callers will be application protocols into which
security enhancements are integrated through invocation of services
provided by the GSS-API. The GSS-API allows a caller application to
authenticate a principal identity associated with a peer application,
to delegate rights to a peer, and to apply security services such as
confidentiality and integrity on a per-message basis.
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1. Introduction
The Generic Security Service Application Programming Interface
[GSSAPI] provides security services to calling applications. It
allows a communicating application to authenticate the user
associated with another application, to delegate rights to another
application, and to apply security services such as confidentiality
and integrity on a per-message basis.
There are four stages to using the GSS-API:
a) The application acquires a set of credentials with which it may
prove its identity to other processes. The application's
credentials vouch for its global identity, which may or may not be
related to any local username under which it may be running.
b) A pair of communicating applications establish a joint security
context using their credentials. The security context is a pair
of GSS-API data structures that contain shared state information,
which is required in order that per-message security services may
be provided. Examples of state that might be shared between
applications as part of a security context are cryptographic keys,
and message sequence numbers. As part of the establishment of a
security context, the context initiator is authenticated to the
responder, and may require that the responder is authenticated in
turn. The initiator may optionally give the responder the right
to initiate further security contexts, acting as an agent or
delegate of the initiator. This transfer of rights is termed
delegation, and is achieved by creating a set of credentials,
similar to those used by the initiating application, but which may
be used by the responder.
To establish and maintain the shared information that makes up the
security context, certain GSS-API calls will return a token data
structure, which is an opaque data type that may contain
cryptographically protected data. The caller of such a GSS-API
routine is responsible for transferring the token to the peer
application, encapsulated if necessary in an application-
application protocol. On receipt of such a token, the peer
application should pass it to a corresponding GSS-API routine
which will decode the token and extract the information, updating
the security context state information accordingly.
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c) Per-message services are invoked to apply either:
integrity and data origin authentication, or confidentiality,
integrity and data origin authentication to application data,
which are treated by GSS-API as arbitrary octet-strings. An
application transmitting a message that it wishes to protect will
call the appropriate GSS-API routine (gss_get_mic or gss_wrap) to
apply protection, specifying the appropriate security context, and
send the resulting token to the receiving application. The
receiver will pass the received token (and, in the case of data
protected by gss_get_mic, the accompanying message-data) to the
corresponding decoding routine (gss_verify_mic or gss_unwrap) to
remove the protection and validate the data.
d) At the completion of a communications session (which may extend
across several transport connections), each application calls a
GSS-API routine to delete the security context. Multiple contexts
may also be used (either successively or simultaneously) within a
single communications association, at the option of the
applications.
2. GSS-API Routines
This section lists the routines that make up the GSS-API, and
offers a brief description of the purpose of each routine.
Detailed descriptions of each routine are listed in alphabetical
order in section 5.
Table 2-1 GSS-API Credential-management Routines
Routine Section Function
------- ------- --------
gss_acquire_cred 5.2 Assume a global identity; Obtain
a GSS-API credential handle for
pre-existing credentials.
gss_add_cred 5.3 Construct credentials
incrementally
gss_inquire_cred 5.21 Obtain information about a
credential
gss_inquire_cred_by_mech 5.22 Obtain per-mechanism information
about a credential.
gss_release_cred 5.27 Discard a credential handle.
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Table 2-2 GSS-API Context-Level Routines
Routine Section Function
------- ------- --------
gss_init_sec_context 5.19 Initiate a security context with
a peer application
gss_accept_sec_context 5.1 Accept a security context
initiated by a
peer application
gss_delete_sec_context 5.9 Discard a security context
gss_process_context_token 5.25 Process a token on a security
context from a peer application
gss_context_time 5.7 Determine for how long a context
will remain valid
gss_inquire_context 5.20 Obtain information about a
security context
gss_wrap_size_limit 5.34 Determine token-size limit for
gss_wrap on a context
gss_export_sec_context 5.14 Transfer a security context to
another process
gss_import_sec_context 5.17 Import a transferred context
Table 2-3 GSS-API Per-message Routines
Routine Section Function
------- ------- --------
gss_get_mic 5.15 Calculate a cryptographic message
integrity code (MIC) for a
message; integrity service
gss_verify_mic 5.32 Check a MIC against a message;
verify integrity of a received
message
gss_wrap 5.33 Attach a MIC to a message, and
optionally encrypt the message
content;
confidentiality service
gss_unwrap 5.31 Verify a message with attached
MIC, and decrypt message content
if necessary.
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Table 2-4 GSS-API Name manipulation Routines
Routine Section Function
------- ------- --------
gss_import_name 5.16 Convert a contiguous string name
to internal-form
gss_display_name 5.10 Convert internal-form name to
text
gss_compare_name 5.6 Compare two internal-form names
gss_release_name 5.28 Discard an internal-form name
gss_inquire_names_for_mech 5.24 List the name-types supported by
the specified mechanism
gss_inquire_mechs_for_name 5.23 List mechanisms that support the
specified name-type
gss_canonicalize_name 5.5 Convert an internal name to an MN
gss_export_name 5.13 Convert an MN to export form
gss_duplicate_name 5.12 Create a copy of an internal name
Table 2-5 GSS-API Miscellaneous Routines
Routine Section Function
------- ------- --------
gss_add_oid_set_member 5.4 Add an object identifier to
a set
gss_display_status 5.11 Convert a GSS-API status code
to text
gss_indicate_mechs 5.18 Determine available underlying
authentication mechanisms
gss_release_buffer 5.26 Discard a buffer
gss_release_oid_set 5.29 Discard a set of object
identifiers
gss_create_empty_oid_set 5.8 Create a set containing no
object identifiers
gss_test_oid_set_member 5.30 Determines whether an object
identifier is a member of a set.
Individual GSS-API implementations may augment these routines by
providing additional mechanism-specific routines if required
functionality is not available from the generic forms. Applications
are encouraged to use the generic routines wherever possible on
portability grounds.
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3. Data Types and Calling Conventions
The following conventions are used by the GSS-API C-language
bindings:
3.1. Integer types
GSS-API uses the following integer data type:
OM_uint32 32-bit unsigned integer
Where guaranteed minimum bit-count is important, this portable data
type is used by the GSS-API routine definitions. Individual GSS-API
implementations will include appropriate typedef definitions to map
this type onto a built-in data type. If the platform supports the
X/Open xom.h header file, the OM_uint32 definition contained therein
should be used; the GSS-API header file in Appendix A contains logic
that will detect the prior inclusion of xom.h, and will not attempt
to re-declare OM_uint32. If the X/Open header file is not available
on the platform, the GSS-API implementation should use the smallest
natural unsigned integer type that provides at least 32 bits of
precision.
3.2. String and similar data
Many of the GSS-API routines take arguments and return values that
describe contiguous octet-strings. All such data is passed between
the GSS-API and the caller using the gss_buffer_t data type. This
data type is a pointer to a buffer descriptor, which consists of a
length field that contains the total number of bytes in the datum,
and a value field which contains a pointer to the actual datum:
typedef struct gss_buffer_desc_struct {
size_t length;
void *value;
} gss_buffer_desc, *gss_buffer_t;
Storage for data returned to the application by a GSS-API routine
using the gss_buffer_t conventions is allocated by the GSS-API
routine. The application may free this storage by invoking the
gss_release_buffer routine. Allocation of the gss_buffer_desc object
is always the responsibility of the application; unused
gss_buffer_desc objects may be initialized to the value
GSS_C_EMPTY_BUFFER.
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3.2.1. Opaque data types
Certain multiple-word data items are considered opaque data types at
the GSS-API, because their internal structure has no significance
either to the GSS-API or to the caller. Examples of such opaque data
types are the input_token parameter to gss_init_sec_context (which is
opaque to the caller), and the input_message parameter to gss_wrap
(which is opaque to the GSS-API). Opaque data is passed between the
GSS-API and the application using the gss_buffer_t datatype.
3.2.2. Character strings
Certain multiple-word data items may be regarded as simple ISO
Latin-1 character strings. Examples are the printable strings passed
to gss_import_name via the input_name_buffer parameter. Some GSS-API
routines also return character strings. All such character strings
are passed between the application and the GSS-API implementation
using the gss_buffer_t datatype, which is a pointer to a
gss_buffer_desc object.
When a gss_buffer_desc object describes a printable string, the
length field of the gss_buffer_desc should only count printable
characters within the string. In particular, a trailing NUL
character should NOT be included in the length count, nor should
either the GSS-API implementation or the application assume the
presence of an uncounted trailing NUL.
3.3. Object Identifiers
Certain GSS-API procedures take parameters of the type gss_OID, or
Object identifier. This is a type containing ISO-defined tree-
structured values, and is used by the GSS-API caller to select an
underlying security mechanism and to specify namespaces. A value of
type gss_OID has the following structure:
typedef struct gss_OID_desc_struct {
OM_uint32 length;
void *elements;
} gss_OID_desc, *gss_OID;
The elements field of this structure points to the first byte of an
octet string containing the ASN.1 BER encoding of the value portion
of the normal BER TLV encoding of the gss_OID. The length field
contains the number of bytes in this value. For example, the gss_OID
value corresponding to {iso(1) identified-organization(3) icd-
ecma(12) member-company(2) dec(1011) cryptoAlgorithms(7) DASS(5)},
meaning the DASS X.509 authentication mechanism, has a length field
of 7 and an elements field pointing to seven octets containing the
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following octal values: 53,14,2,207,163,7,5. GSS-API implementations
should provide constant gss_OID values to allow applications to
request any supported mechanism, although applications are encouraged
on portability grounds to accept the default mechanism. gss_OID
values should also be provided to allow applications to specify
particular name types (see section 3.10). Applications should treat
gss_OID_desc values returned by GSS-API routines as read-only. In
particular, the application should not attempt to deallocate them
with free(). The gss_OID_desc datatype is equivalent to the X/Open
OM_object_identifier datatype[XOM].
3.4. Object Identifier Sets
Certain GSS-API procedures take parameters of the type gss_OID_set.
This type represents one or more object identifiers (section 2.3). A
gss_OID_set object has the following structure:
typedef struct gss_OID_set_desc_struct {
size_t count;
gss_OID elements;
} gss_OID_set_desc, *gss_OID_set;
The count field contains the number of OIDs within the set. The
elements field is a pointer to an array of gss_OID_desc objects, each
of which describes a single OID. gss_OID_set values are used to name
the available mechanisms supported by the GSS-API, to request the use
of specific mechanisms, and to indicate which mechanisms a given
credential supports.
All OID sets returned to the application by GSS-API are dynamic
objects (the gss_OID_set_desc, the "elements" array of the set, and
the "elements" array of each member OID are all dynamically
allocated), and this storage must be deallocated by the application
using the gss_release_oid_set() routine.
3.5. Credentials
A credential handle is a caller-opaque atomic datum that identifies a
GSS-API credential data structure. It is represented by the caller-
opaque type gss_cred_id_t, which should be implemented as a pointer
or arithmetic type. If a pointer implementation is chosen, care must
be taken to ensure that two gss_cred_id_t values may be compared with
the == operator.
GSS-API credentials can contain mechanism-specific principal
authentication data for multiple mechanisms. A GSS-API credential is
composed of a set of credential-elements, each of which is applicable
to a single mechanism. A credential may contain at most one
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credential-element for each supported mechanism. A credential-element
identifies the data needed by a single mechanism to authenticate a
single principal, and conceptually contains two credential-references
that describe the actual mechanism-specific authentication data, one
to be used by GSS-API for initiating contexts, and one to be used
for accepting contexts. For mechanisms that do not distinguish
between acceptor and initiator credentials, both references would
point to the same underlying mechanism-specific authentication data.
Credentials describe a set of mechanism-specific principals, and give
their holder the ability to act as any of those principals. All
principal identities asserted by a single GSS-API credential should
belong to the same entity, although enforcement of this property is
an implementation-specific matter. The GSS-API does not make the
actual credentials available to applications; instead a credential
handle is used to identify a particular credential, held internally
by GSS-API. The combination of GSS-API credential handle and
mechanism identifies the principal whose identity will be asserted by
the credential when used with that mechanism.
The gss_init_sec_context and gss_accept_sec_context routines allow
the value GSS_C_NO_CREDENTIAL to be specified as their credential
handle parameter. This special credential-handle indicates a desire
by the application to act as a default principal. While individual
GSS-API implementations are free to determine such default behavior
as appropriate to the mechanism, the following default behavior by
these routines is recommended for portability:
gss_init_sec_context
1) If there is only a single principal capable of initiating
security contexts for the chosen mechanism that the application
is authorized to act on behalf of, then that principal shall be
used, otherwise
2) If the platform maintains a concept of a default network-
identity for the chosen mechanism, and if the application is
authorized to act on behalf of that identity for the purpose of
initiating security contexts, then the principal corresponding
to that identity shall be used, otherwise
3) If the platform maintains a concept of a default local
identity, and provides a means to map local identities into
network-identities for the chosen mechanism, and if the
application is authorized to act on behalf of the network-
identity image of the default local identity for the purpose of
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initiating security contexts using the chosen mechanism, then
the principal corresponding to that identity shall be used,
otherwise
4) A user-configurable default identity should be used.
gss_accept_sec_context
1) If there is only a single authorized principal identity capable
of accepting security contexts for the chosen mechanism, then
that principal shall be used, otherwise
2) If the mechanism can determine the identity of the target
principal by examining the context-establishment token, and if
the accepting application is authorized to act as that
principal for the purpose of accepting security contexts using
the chosen mechanism, then that principal identity shall be
used, otherwise
3) If the mechanism supports context acceptance by any principal,
and if mutual authentication was not requested, any principal
that the application is authorized to accept security contexts
under using the chosen mechanism may be used, otherwise
4)A user-configurable default identity shall be used.
The purpose of the above rules is to allow security contexts to be
established by both initiator and acceptor using the default behavior
wherever possible. Applications requesting default behavior are
likely to be more portable across mechanisms and platforms than ones
that use gss_acquire_cred to request a specific identity.
3.6. Contexts
The gss_ctx_id_t data type contains a caller-opaque atomic value that
identifies one end of a GSS-API security context. It should be
implemented as a pointer or arithmetic type. If a pointer type is
chosen, care should be taken to ensure that two gss_ctx_id_t values
may be compared with the == operator.
The security context holds state information about each end of a peer
communication, including cryptographic state information.
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3.7. Authentication tokens
A token is a caller-opaque type that GSS-API uses to maintain
synchronization between the context data structures at each end of a
GSS-API security context. The token is a cryptographically protected
octet-string, generated by the underlying mechanism at one end of a
GSS-API security context for use by the peer mechanism at the other
end. Encapsulation (if required) and transfer of the token are the
responsibility of the peer applications. A token is passed between
the GSS-API and the application using the gss_buffer_t conventions.
3.8. Interprocess tokens
Certain GSS-API routines are intended to transfer data between
processes in multi-process programs. These routines use a caller-
opaque octet-string, generated by the GSS-API in one process for use
by the GSS-API in another process. The calling application is
responsible for transferring such tokens between processes in an OS-
specific manner. Note that, while GSS-API implementors are
encouraged to avoid placing sensitive information within interprocess
tokens, or to cryptographically protect them, many implementations
will be unable to avoid placing key material or other sensitive data
within them. It is the application's responsibility to ensure that
interprocess tokens are protected in transit, and transferred only to
processes that are trustworthy. An interprocess token is passed
between the GSS-API and the application using the gss_buffer_t
conventions.
3.9. Status values
Every GSS-API routine returns two distinct values to report status
information to the caller: GSS status codes and Mechanism status
codes.
3.9.1. GSS status codes
GSS-API routines return GSS status codes as their OM_uint32 function
value. These codes indicate errors that are independent of the
underlying mechanism(s) used to provide the security service. The
errors that can be indicated via a GSS status code are either generic
API routine errors (errors that are defined in the GSS-API
specification) or calling errors (errors that are specific to these
language bindings).
A GSS status code can indicate a single fatal generic API error from
the routine and a single calling error. In addition, supplementary
status information may be indicated via the setting of bits in the
supplementary info field of a GSS status code.
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These errors are encoded into the 32-bit GSS status code as follows:
MSB LSB
|------------------------------------------------------------|
| Calling Error | Routine Error | Supplementary Info |
|------------------------------------------------------------|
Bit 31 24 23 16 15 0
Hence if a GSS-API routine returns a GSS status code whose upper 16
bits contain a non-zero value, the call failed. If the calling error
field is non-zero, the invoking application's call of the routine was
erroneous. Calling errors are defined in table 5-1. If the routine
error field is non-zero, the routine failed for one of the routine-
specific reasons listed below in table 5-2. Whether or not the upper
16 bits indicate a failure or a success, the routine may indicate
additional information by setting bits in the supplementary info
field of the status code. The meaning of individual bits is listed
below in table 5-3.
Table 3-1 Calling Errors
Name Value in field Meaning
---- -------------- -------
GSS_S_CALL_INACCESSIBLE_READ 1 A required input parameter
could not be read
GSS_S_CALL_INACCESSIBLE_WRITE 2 A required output parameter
could not be written.
GSS_S_CALL_BAD_STRUCTURE 3 A parameter was malformed
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Table 3-2 Routine Errors
Name Value in field Meaning
---- -------------- -------
GSS_S_BAD_MECH 1 An unsupported mechanism
was requested
GSS_S_BAD_NAME 2 An invalid name was
supplied
GSS_S_BAD_NAMETYPE 3 A supplied name was of an
unsupported type
GSS_S_BAD_BINDINGS 4 Incorrect channel bindings
were supplied
GSS_S_BAD_STATUS 5 An invalid status code was
supplied
GSS_S_BAD_MIC GSS_S_BAD_SIG 6 A token had an invalid MIC
GSS_S_NO_CRED 7 No credentials were
supplied, or the
credentials were
unavailable or
inaccessible.
GSS_S_NO_CONTEXT 8 No context has been
established
GSS_S_DEFECTIVE_TOKEN 9 A token was invalid
GSS_S_DEFECTIVE_CREDENTIAL 10 A credential was invalid
GSS_S_CREDENTIALS_EXPIRED 11 The referenced credentials
have expired
GSS_S_CONTEXT_EXPIRED 12 The context has expired
GSS_S_FAILURE 13 Miscellaneous failure (see
text)
GSS_S_BAD_QOP 14 The quality-of-protection
requested could not be
provided
GSS_S_UNAUTHORIZED 15 The operation is forbidden
by local security policy
GSS_S_UNAVAILABLE 16 The operation or option is
unavailable
GSS_S_DUPLICATE_ELEMENT 17 The requested credential
element already exists
GSS_S_NAME_NOT_MN 18 The provided name was not a
mechanism name
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Table 3-3 Supplementary Status Bits
Name Bit Number Meaning
---- ---------- -------
GSS_S_CONTINUE_NEEDED 0 (LSB) Returned only by
gss_init_sec_context or
gss_accept_sec_context. The
routine must be called again
to complete its function.
See routine documentation for
detailed description
GSS_S_DUPLICATE_TOKEN 1 The token was a duplicate of
an earlier token
GSS_S_OLD_TOKEN 2 The token's validity period
has expired
GSS_S_UNSEQ_TOKEN 3 A later token has already been
processed
GSS_S_GAP_TOKEN 4 An expected per-message token
was not received
The routine documentation also uses the name GSS_S_COMPLETE, which is
a zero value, to indicate an absence of any API errors or
supplementary information bits.
All GSS_S_xxx symbols equate to complete OM_uint32 status codes,
rather than to bitfield values. For example, the actual value of the
symbol GSS_S_BAD_NAMETYPE (value 3 in the routine error field) is
3<<16. The macros GSS_CALLING_ERROR(), GSS_ROUTINE_ERROR() and
GSS_SUPPLEMENTARY_INFO() are provided, each of which takes a GSS
status code and removes all but the relevant field. For example, the
value obtained by applying GSS_ROUTINE_ERROR to a status code removes
the calling errors and supplementary info fields, leaving only the
routine errors field. The values delivered by these macros may be
directly compared with a GSS_S_xxx symbol of the appropriate type.
The macro GSS_ERROR() is also provided, which when applied to a GSS
status code returns a non-zero value if the status code indicated a
calling or routine error, and a zero value otherwise. All macros
defined by GSS-API evaluate their argument(s) exactly once.
A GSS-API implementation may choose to signal calling errors in a
platform-specific manner instead of, or in addition to the routine
value; routine errors and supplementary info should be returned via
major status values only.
The GSS major status code GSS_S_FAILURE is used to indicate that the
underlying mechanism detected an error for which no specific GSS
status code is defined. The mechanism-specific status code will
provide more details about the error.
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3.9.2. Mechanism-specific status codes
GSS-API routines return a minor_status parameter, which is used to
indicate specialized errors from the underlying security mechanism.
This parameter may contain a single mechanism-specific error,
indicated by a OM_uint32 value.
The minor_status parameter will always be set by a GSS-API routine,
even if it returns a calling error or one of the generic API errors
indicated above as fatal, although most other output parameters may
remain unset in such cases. However, output parameters that are
expected to return pointers to storage allocated by a routine must
always be set by the routine, even in the event of an error, although
in such cases the GSS-API routine may elect to set the returned
parameter value to NULL to indicate that no storage was actually
allocated. Any length field associated with such pointers (as in a
gss_buffer_desc structure) should also be set to zero in such cases.
3.10. Names
A name is used to identify a person or entity. GSS-API authenticates
the relationship between a name and the entity claiming the name.
Since different authentication mechanisms may employ different
namespaces for identifying their principals, GSSAPI's naming support
is necessarily complex in multi-mechanism environments (or even in
some single-mechanism environments where the underlying mechanism
supports multiple namespaces).
Two distinct representations are defined for names:
An internal form. This is the GSS-API "native" format for names,
represented by the implementation-specific gss_name_t type. It is
opaque to GSS-API callers. A single gss_name_t object may contain
multiple names from different namespaces, but all names should
refer to the same entity. An example of such an internal name
would be the name returned from a call to the gss_inquire_cred
routine, when applied to a credential containing credential
elements for multiple authentication mechanisms employing
different namespaces. This gss_name_t object will contain a
distinct name for the entity for each authentication mechanism.
For GSS-API implementations supporting multiple namespaces,
objects of type gss_name_t must contain sufficient information to
determine the namespace to which each primitive name belongs.
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Mechanism-specific contiguous octet-string forms. A format
capable of containing a single name (from a single namespace).
Contiguous string names are always accompanied by an object
identifier specifying the namespace to which the name belongs, and
their format is dependent on the authentication mechanism that
employs the name. Many, but not all, contiguous string names will
be printable, and may therefore be used by GSS-API applications
for communication with their users.
Routines (gss_import_name and gss_display_name) are provided to
convert names between contiguous string representations and the
internal gss_name_t type. gss_import_name may support multiple
syntaxes for each supported namespace, allowing users the freedom to
choose a preferred name representation. gss_display_name should use
an implementation-chosen printable syntax for each supported name-
type.
If an application calls gss_display_name(), passing the internal name
resulting from a call to gss_import_name(), there is no guarantee the
the resulting contiguous string name will be the same as the original
imported string name. Nor do name-space identifiers necessarily
survive unchanged after a journey through the internal name-form. An
example of this might be a mechanism that authenticates X.500 names,
but provides an algorithmic mapping of Internet DNS names into X.500.
That mechanism's implementation of gss_import_name() might, when
presented with a DNS name, generate an internal name that contained
both the original DNS name and the equivalent X.500 name.
Alternatively, it might only store the X.500 name. In the latter
case, gss_display_name() would most likely generate a printable X.500
name, rather than the original DNS name.
The process of authentication delivers to the context acceptor an
internal name. Since this name has been authenticated by a single
mechanism, it contains only a single name (even if the internal name
presented by the context initiator to gss_init_sec_context had
multiple components). Such names are termed internal mechanism
names, or "MN"s and the names emitted by gss_accept_sec_context() are
always of this type. Since some applications may require MNs without
wanting to incur the overhead of an authentication operation, a
second function, gss_canonicalize_name(), is provided to convert a
general internal name into an MN.
Comparison of internal-form names may be accomplished via the
gss_compare_name() routine, which returns true if the two names being
compared refer to the same entity. This removes the need for the
application program to understand the syntaxes of the various
printable names that a given GSS-API implementation may support.
Since GSS-API assumes that all primitive names contained within a
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given internal name refer to the same entity, gss_compare_name() can
return true if the two names have at least one primitive name in
common. If the implementation embodies knowledge of equivalence
relationships between names taken from different namespaces, this
knowledge may also allow successful comparison of internal names
containing no overlapping primitive elements.
When used in large access control lists, the overhead of invoking
gss_import_name() and gss_compare_name() on each name from the ACL
may be prohibitive. As an alternative way of supporting this case,
GSS-API defines a special form of the contiguous string name which
may be compared directly (e.g. with memcmp()). Contiguous names
suitable for comparison are generated by the gss_export_name()
routine, which requires an MN as input. Exported names may be re-
imported by the gss_import_name() routine, and the resulting internal
name will also be an MN. The gss_OID constant GSS_C_NT_EXPORT_NAME
indentifies the "export name" type, and the value of this constant is
given in Appendix A. Structurally, an exported name object consists
of a header containing an OID identifying the mechanism that
authenticated the name, and a trailer containing the name itself,
where the syntax of the trailer is defined by the individual
mechanism specification. The precise format of an export name is
defined in the language-independent GSS-API specification [GSSAPI].
Note that the results obtained by using gss_compare_name() will in
general be different from those obtained by invoking
gss_canonicalize_name() and gss_export_name(), and then comparing the
exported names. The first series of operation determines whether two
(unauthenticated) names identify the same principal; the second
whether a particular mechanism would authenticate them as the same
principal. These two operations will in general give the same
results only for MNs.
The gss_name_t datatype should be implemented as a pointer type. To
allow the compiler to aid the application programmer by performing
type-checking, the use of (void *) is discouraged. A pointer to an
implementation-defined type is the preferred choice.
Storage is allocated by routines that return gss_name_t values. A
procedure, gss_release_name, is provided to free storage associated
with an internal-form name.
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3.11. Channel Bindings
GSS-API supports the use of user-specified tags to identify a given
context to the peer application. These tags are intended to be used
to identify the particular communications channel that carries the
context. Channel bindings are communicated to the GSS-API using the
following structure:
typedef struct gss_channel_bindings_struct {
OM_uint32 initiator_addrtype;
gss_buffer_desc initiator_address;
OM_uint32 acceptor_addrtype;
gss_buffer_desc acceptor_address;
gss_buffer_desc application_data;
} *gss_channel_bindings_t;
The initiator_addrtype and acceptor_addrtype fields denote the type
of addresses contained in the initiator_address and acceptor_address
buffers. The address type should be one of the following:
GSS_C_AF_UNSPEC Unspecified address type
GSS_C_AF_LOCAL Host-local address type
GSS_C_AF_INET Internet address type (e.g. IP)
GSS_C_AF_IMPLINK ARPAnet IMP address type
GSS_C_AF_PUP pup protocols (eg BSP) address type
GSS_C_AF_CHAOS MIT CHAOS protocol address type
GSS_C_AF_NS XEROX NS address type
GSS_C_AF_NBS nbs address type
GSS_C_AF_ECMA ECMA address type
GSS_C_AF_DATAKIT datakit protocols address type
GSS_C_AF_CCITT CCITT protocols
GSS_C_AF_SNA IBM SNA address type
GSS_C_AF_DECnet DECnet address type
GSS_C_AF_DLI Direct data link interface address type
GSS_C_AF_LAT LAT address type
GSS_C_AF_HYLINK NSC Hyperchannel address type
GSS_C_AF_APPLETALK AppleTalk address type
GSS_C_AF_BSC BISYNC 2780/3780 address type
GSS_C_AF_DSS Distributed system services address type
GSS_C_AF_OSI OSI TP4 address type
GSS_C_AF_X25 X.25
GSS_C_AF_NULLADDR No address specified
Note that these symbols name address families rather than specific
addressing formats. For address families that contain several
alternative address forms, the initiator_address and acceptor_address
fields must contain sufficient information to determine which address
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form is used. When not otherwise specified, addresses should be
specified in network byte-order (that is, native byte-ordering for
the address family).
Conceptually, the GSS-API concatenates the initiator_addrtype,
initiator_address, acceptor_addrtype, acceptor_address and
application_data to form an octet string. The mechanism calculates a
MIC over this octet string, and binds the MIC to the context
establishment token emitted by gss_init_sec_context. The same
bindings are presented by the context acceptor to
gss_accept_sec_context, and a MIC is calculated in the same way. The
calculated MIC is compared with that found in the token, and if the
MICs differ, gss_accept_sec_context will return a GSS_S_BAD_BINDINGS
error, and the context will not be established. Some mechanisms may
include the actual channel binding data in the token (rather than
just a MIC); applications should therefore not use confidential data
as channel-binding components.
Individual mechanisms may impose additional constraints on addresses
and address types that may appear in channel bindings. For example,
a mechanism may verify that the initiator_address field of the
channel bindings presented to gss_init_sec_context contains the
correct network address of the host system. Portable applications
should therefore ensure that they either provide correct information
for the address fields, or omit addressing information, specifying
GSS_C_AF_NULLADDR as the address-types.
3.12. Optional parameters
Various parameters are described as optional. This means that they
follow a convention whereby a default value may be requested. The
following conventions are used for omitted parameters. These
conventions apply only to those parameters that are explicitly
documented as optional.
3.12.1. gss_buffer_t types
Specify GSS_C_NO_BUFFER as a value. For an input parameter this
signifies that default behavior is requested, while for an output
parameter it indicates that the information that would be returned
via the parameter is not required by the application.
3.12.2. Integer types (input)
Individual parameter documentation lists values to be used to
indicate default actions.
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3.12.3. Integer types (output)
Specify NULL as the value for the pointer.
3.12.4. Pointer types
Specify NULL as the value.
3.12.5. Object IDs
Specify GSS_C_NO_OID as the value.
3.12.6. Object ID Sets
Specify GSS_C_NO_OID_SET as the value.
3.12.7. Channel Bindings
Specify GSS_C_NO_CHANNEL_BINDINGS to indicate that channel bindings
are not to be used.
4. Additional Controls
This section discusses the optional services that a context initiator
may request of the GSS-API at context establishment. Each of these
services is requested by setting a flag in the req_flags input
parameter to gss_init_sec_context.
The optional services currently defined are:
Delegation - The (usually temporary) transfer of rights from
initiator to acceptor, enabling the acceptor to authenticate
itself as an agent of the initiator.
Mutual Authentication - In addition to the initiator authenticating
its identity to the context acceptor, the context acceptor should
also authenticate itself to the initiator.
Replay detection - In addition to providing message integrity
services, gss_get_mic and gss_wrap should include message
numbering information to enable gss_verify_mic and gss_unwrap to
detect if a message has been duplicated.
Out-of-sequence detection - In addition to providing message
integrity services, gss_get_mic and gss_wrap should include
message sequencing information to enable gss_verify_mic and
gss_unwrap to detect if a message has been received out of
sequence.
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Anonymous authentication - The establishment of the security context
should not reveal the initiator's identity to the context
acceptor.
Any currently undefined bits within such flag arguments should be
ignored by GSS-API implementations when presented by an application,
and should be set to zero when returned to the application by the
GSS-API implementation.
Some mechanisms may not support all optional services, and some
mechanisms may only support some services in conjunction with others.
Both gss_init_sec_context and gss_accept_sec_context inform the
applications which services will be available from the context when
the establishment phase is complete, via the ret_flags output
parameter. In general, if the security mechanism is capable of
providing a requested service, it should do so, even if additional
services must be enabled in order to provide the requested service.
If the mechanism is incapable of providing a requested service, it
should proceed without the service, leaving the application to abort
the context establishment process if it considers the requested
service to be mandatory.
Some mechanisms may specify that support for some services is
optional, and that implementors of the mechanism need not provide it.
This is most commonly true of the confidentiality service, often
because of legal restrictions on the use of data-encryption, but may
apply to any of the services. Such mechanisms are required to send
at least one token from acceptor to initiator during context
establishment when the initiator indicates a desire to use such a
service, so that the initiating GSS-API can correctly indicate
whether the service is supported by the acceptor's GSS-API.
4.1. Delegation
The GSS-API allows delegation to be controlled by the initiating
application via a boolean parameter to gss_init_sec_context(), the
routine that establishes a security context. Some mechanisms do not
support delegation, and for such mechanisms attempts by an
application to enable delegation are ignored.
The acceptor of a security context for which the initiator enabled
delegation will receive (via the delegated_cred_handle parameter of
gss_accept_sec_context) a credential handle that contains the
delegated identity, and this credential handle may be used to
initiate subsequent GSS-API security contexts as an agent or delegate
of the initiator. If the original initiator's identity is "A" and
the delegate's identity is "B", then, depending on the underlying
mechanism, the identity embodied by the delegated credential may be
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either "A" or "B acting for A".
For many mechanisms that support delegation, a simple boolean does
not provide enough control. Examples of additional aspects of
delegation control that a mechanism might provide to an application
are duration of delegation, network addresses from which delegation
is valid, and constraints on the tasks that may be performed by a
delegate. Such controls are presently outside the scope of the GSS-
API. GSS-API implementations supporting mechanisms offering
additional controls should provide extension routines that allow
these controls to be exercised (perhaps by modifying the initiator's
GSS-API credential prior to its use in establishing a context).
However, the simple delegation control provided by GSS-API should
always be able to over-ride other mechanism-specific delegation
controls - If the application instructs gss_init_sec_context() that
delegation is not desired, then the implementation must not permit
delegation to occur. This is an exception to the general rule that a
mechanism may enable services even if they are not requested -
delegation may only be provided at the explicit request of the
application.
4.2. Mutual authentication
Usually, a context acceptor will require that a context initiator
authenticate itself so that the acceptor may make an access-control
decision prior to performing a service for the initiator. In some
cases, the initiator may also request that the acceptor authenticate
itself. GSS-API allows the initiating application to request this
mutual authentication service by setting a flag when calling
gss_init_sec_context.
The initiating application is informed as to whether or not the
context acceptor has authenticated itself. Note that some mechanisms
may not support mutual authentication, and other mechanisms may
always perform mutual authentication, whether or not the initiating
application requests it. In particular, mutual authentication my be
required by some mechanisms in order to support replay or out-of-
sequence message detection, and for such mechanisms a request for
either of these services will automatically enable mutual
authentication.
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4.3. Replay and out-of-sequence detection
The GSS-API may provide detection of mis-ordered message once a
security context has been established. Protection may be applied to
messages by either application, by calling either gss_get_mic or
gss_wrap, and verified by the peer application by calling
gss_verify_mic or gss_unwrap.
gss_get_mic calculates a cryptographic MIC over an application
message, and returns that MIC in a token. The application should
pass both the token and the message to the peer application, which
presents them to gss_verify_mic.
gss_wrap calculates a cryptographic MIC of an application message,
and places both the MIC and the message inside a single token. The
Application should pass the token to the peer application, which
presents it to gss_unwrap to extract the message and verify the MIC.
Either pair of routines may be capable of detecting out-of-sequence
message delivery, or duplication of messages. Details of such mis-
ordered messages are indicated through supplementary status bits in
the major status code returned by gss_verify_mic or gss_unwrap. The
relevant supplementary bits are:
GSS_S_DUPLICATE_TOKEN - The token is a duplicate of one that has
already been received and processed. Only
contexts that claim to provide replay detection
may set this bit.
GSS_S_OLD_TOKEN - The token is too old to determine whether or
not it is a duplicate. Contexts supporting
out-of-sequence detection but not replay
detection should always set this bit if
GSS_S_UNSEQ_TOKEN is set; contexts that support
replay detection should only set this bit if the
token is so old that it cannot be checked for
duplication.
GSS_S_UNSEQ_TOKEN - A later token has already been processed.
GSS_S_GAP_TOKEN - An earlier token has not yet been received.
A mechanism need not maintain a list of all tokens that have been
processed in order to support these status codes. A typical
mechanism might retain information about only the most recent "N"
tokens processed, allowing it to distinguish duplicates and missing
tokens within the most recent "N" messages; the receipt of a token
older than the most recent "N" would result in a GSS_S_OLD_TOKEN
status.
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4.4. Anonymous Authentication
In certain situations, an application may wish to initiate the
authentication process to authenticate a peer, without revealing its
own identity. As an example, consider an application providing
access to a database containing medical information, and offering
unrestricted access to the service. A client of such a service might
wish to authenticate the service (in order to establish trust in any
information retrieved from it), but might not wish the service to be
able to obtain the client's identity (perhaps due to privacy concerns
about the specific inquiries, or perhaps simply to avoid being placed
on mailing-lists).
In normal use of the GSS-API, the initiator's identity is made
available to the acceptor as a result of the context establishment
process. However, context initiators may request that their identity
not be revealed to the context acceptor. Many mechanisms do not
support anonymous authentication, and for such mechanisms the request
will not be honored. An authentication token will be still be
generated, but the application is always informed if a requested
service is unavailable, and has the option to abort context
establishment if anonymity is valued above the other security
services that would require a context to be established.
In addition to informing the application that a context is
established anonymously (via the ret_flags outputs from
gss_init_sec_context and gss_accept_sec_context), the optional
src_name output from gss_accept_sec_context and gss_inquire_context
will, for such contexts, return a reserved internal-form name,
defined by the implementation.
When presented to gss_display_name, this reserved internal-form name
will result in a printable name that is syntactically distinguishable
from any valid principal name supported by the implementation,
associated with a name-type object identifier with the value
GSS_C_NT_ANONYMOUS, whose value us given in Appendix A. The
printable form of an anonymous name should be chosen such that it
implies anonymity, since this name may appear in, for example, audit
logs. For example, the string "" might be a good choice,
if no valid printable names supported by the implementation can begin
with "".
4.5. Confidentiality
If a context supports the confidentiality service, gss_wrap may be
used to encrypt application messages. Messages are selectively
encrypted, under the control of the conf_req_flag input parameter to
gss_wrap.
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4.6. Inter-process context transfer
GSS-API V2 provides routines (gss_export_sec_context and
gss_import_sec_context) which allow a security context to be
transferred between processes on a single machine. The most common
use for such a feature is a client-server design where the server is
implemented as a single process that accepts incoming security
contexts, which then launches child processes to deal with the data
on these contexts. In such a design, the child processes must have
access to the security context data structure created within the
parent by its call to gss_accept_sec_context so that they can use
per-message protection services and delete the security context when
the communication session ends.
Since the security context data structure is expected to contain
sequencing information, it is impractical in general to share a
context between processes. Thus GSS-API provides a call
(gss_export_sec_context) that the process which currently owns the
context can call to declare that it has no intention to use the
context subsequently, and to create an inter-process token containing
information needed by the adopting process to successfully import the
context. After successful completion of gss_export_sec_context, the
original security context is made inaccessible to the calling process
by GSS-API, and any context handles referring to this context are no
longer valid. The originating process transfers the inter-process
token to the adopting process, which passes it to
gss_import_sec_context, and a fresh gss_ctx_id_t is created such that
it is functionally identical to the original context.
The inter-process token may contain sensitive data from the original
security context (including cryptographic keys). Applications using
inter-process tokens to transfer security contexts must take
appropriate steps to protect these tokens in transit.
Implementations are not required to support the inter-process
transfer of security contexts. The ability to transfer a security
context is indicated when the context is created, by
gss_init_sec_context or gss_accept_sec_context setting the
GSS_C_TRANS_FLAG bit in their ret_flags parameter.
4.7. The use of incomplete contexts
Some mechanisms may allow the per-message services to be used before
the context establishment process is complete. For example, a
mechanism may include sufficient information in its initial context-
level token for the context acceptor to immediately decode messages
protected with gss_wrap or gss_get_mic. For such a mechanism, the
initiating application need not wait until subsequent context-level
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tokens have been sent and received before invoking the per-message
protection services.
The ability of a context to provide per-message services in advance
of complete context establishment is indicated by the setting of the
GSS_C_PROT_READY_FLAG bit in the ret_flags parameter from
gss_init_sec_context and gss_accept_sec_context. Applications wishing
to use per-message protection services on partially-established
contexts should check this flag before attempting to invoke gss_wrap
or gss_get_mic.
5. GSS-API Routine Descriptions
In addition to the explicit major status codes documented here, the
code GSS_S_FAILURE may be returned by any routine, indicating an
implementation-specific or mechanism-specific error condition,
further details of which are reported via the minor_status parameter.
5.1. gss_accept_sec_context
OM_uint32 gss_accept_sec_context (
OM_uint32 *minor_status,
gss_ctx_id_t *context_handle,
const gss_cred_id_t acceptor_cred_handle,
const gss_buffer_t input_token_buffer,
const gss_channel_bindings_t input_chan_bindings,
const gss_name_t *src_name,
gss_OID *mech_type,
gss_buffer_t output_token,
OM_uint32 *ret_flags,
OM_uint32 *time_rec,
gss_cred_id_t *delegated_cred_handle)
Purpose:
Allows a remotely initiated security context between the application
and a remote peer to be established. The routine may return a
output_token which should be transferred to the peer application,
where the peer application will present it to gss_init_sec_context.
If no token need be sent, gss_accept_sec_context will indicate this
by setting the length field of the output_token argument to zero. To
complete the context establishment, one or more reply tokens may be
required from the peer application; if so, gss_accept_sec_context
will return a status flag of GSS_S_CONTINUE_NEEDED, in which case it
should be called again when the reply token is received from the peer
application, passing the token to gss_accept_sec_context via the
input_token parameters.
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Portable applications should be constructed to use the token length
and return status to determine whether a token needs to be sent or
waited for. Thus a typical portable caller should always invoke
gss_accept_sec_context within a loop:
gss_ctx_id_t context_hdl = GSS_C_NO_CONTEXT;
do {
receive_token_from_peer(input_token);
maj_stat = gss_accept_sec_context(&min_stat,
&context_hdl,
cred_hdl,
input_token,
input_bindings,
&client_name,
&mech_type,
output_token,
&ret_flags,
&time_rec,
&deleg_cred);
if (GSS_ERROR(maj_stat)) {
report_error(maj_stat, min_stat);
};
if (output_token->length != 0) {
send_token_to_peer(output_token);
gss_release_buffer(&min_stat, output_token);
};
if (GSS_ERROR(maj_stat)) {
if (context_hdl != GSS_C_NO_CONTEXT)
gss_delete_sec_context(&min_stat,
&context_hdl,
GSS_C_NO_BUFFER);
break;
};
} while (maj_stat & GSS_S_CONTINUE_NEEDED);
Whenever the routine returns a major status that includes the value
GSS_S_CONTINUE_NEEDED, the context is not fully established and the
following restrictions apply to the output parameters:
The value returned via the time_rec parameter is undefined Unless the
accompanying ret_flags parameter contains the bit
GSS_C_PROT_READY_FLAG, indicating that per-message services may be
applied in advance of a successful completion status, the value
returned via the mech_type parameter may be undefined until the
routine returns a major status value of GSS_S_COMPLETE.
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The values of the GSS_C_DELEG_FLAG,
GSS_C_MUTUAL_FLAG,GSS_C_REPLAY_FLAG, GSS_C_SEQUENCE_FLAG,
GSS_C_CONF_FLAG,GSS_C_INTEG_FLAG and GSS_C_ANON_FLAG bits returned
via the ret_flags parameter should contain the values that the
implementation expects would be valid if context establishment were
to succeed.
The values of the GSS_C_PROT_READY_FLAG and GSS_C_TRANS_FLAG bits
within ret_flags should indicate the actual state at the time
gss_accept_sec_context returns, whether or not the context is fully
established.
Although this requires that GSS-API implementations set the
GSS_C_PROT_READY_FLAG in the final ret_flags returned to a caller
(i.e. when accompanied by a GSS_S_COMPLETE status code), applications
should not rely on this behavior as the flag was not defined in
Version 1 of the GSS-API. Instead, applications should be prepared to
use per-message services after a successful context establishment,
according to the GSS_C_INTEG_FLAG and GSS_C_CONF_FLAG values.
All other bits within the ret_flags argument should be set to zero.
While the routine returns GSS_S_CONTINUE_NEEDED, the values returned
via the ret_flags argument indicate the services that the
implementation expects to be available from the established context.
If the initial call of gss_accept_sec_context() fails, the
implementation should not create a context object, and should leave
the value of the context_handle parameter set to GSS_C_NO_CONTEXT to
indicate this. In the event of a failure on a subsequent call, the
implementation is permitted to delete the "half-built" security
context (in which case it should set the context_handle parameter to
GSS_C_NO_CONTEXT), but the preferred behavior is to leave the
security context (and the context_handle parameter) untouched for the
application to delete (using gss_delete_sec_context).
During context establishment, the informational status bits
GSS_S_OLD_TOKEN and GSS_S_DUPLICATE_TOKEN indicate fatal errors, and
GSS-API mechanisms should always return them in association with a
routine error of GSS_S_FAILURE. This requirement for pairing did not
exist in version 1 of the GSS-API specification, so applications that
wish to run over version 1 implementations must special-case these
codes.
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Parameters:
context_handle gss_ctx_id_t, read/modify context handle for new
context. Supply GSS_C_NO_CONTEXT for first
call; use value returned in subsequent calls.
Once gss_accept_sec_context() has returned a
value via this parameter, resources have been
assigned to the corresponding context, and must
be freed by the application after use with a
call to gss_delete_sec_context().
acceptor_cred_handle gss_cred_id_t, read Credential handle claimed
by context acceptor. Specify
GSS_C_NO_CREDENTIAL to accept the context as a
default principal. If GSS_C_NO_CREDENTIAL is
specified, but no default acceptor principal is
defined, GSS_S_NO_CRED will be returned.
input_token_buffer buffer, opaque, read token obtained from remote
application.
input_chan_bindings channel bindings, read, optional Application-
specified bindings. Allows application to
securely bind channel identification information
to the security context. If channel bindings
are not used, specify GSS_C_NO_CHANNEL_BINDINGS.
src_name gss_name_t, modify, optional Authenticated name
of context initiator. After use, this name
should be deallocated by passing it to
gss_release_name(). If not required, specify
NULL.
mech_type Object ID, modify, optional Security mechanism
used. The returned OID value will be a pointer
into static storage, and should be treated as
read-only by the caller (in particular, it does
not need to be freed). If not required, specify
NULL.
output_token buffer, opaque, modify Token to be passed to
peer application. If the length field of the
returned token buffer is 0, then no token need
be passed to the peer application. If a non-
zero length field is returned, the associated
storage must be freed after use by the
application with a call to gss_release_buffer().
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ret_flags bit-mask, modify, optional Contains various
independent flags, each of which indicates that
the context supports a specific service option.
If not needed, specify NULL. Symbolic names are
provided for each flag, and the symbolic names
corresponding to the required flags should be
logically-ANDed with the ret_flags value to test
whether a given option is supported by the
context. The flags are:
GSS_C_DELEG_FLAG
True - Delegated credentials are available
via the delegated_cred_handle
parameter
False - No credentials were delegated
GSS_C_MUTUAL_FLAG
True - Remote peer asked for mutual
authentication
False - Remote peer did not ask for mutual
authentication
GSS_C_REPLAY_FLAG
True - replay of protected messages
will be detected
False - replayed messages will not be
detected
GSS_C_SEQUENCE_FLAG
True - out-of-sequence protected
messages will be detected
False - out-of-sequence messages will not
be detected
GSS_C_CONF_FLAG
True - Confidentiality service may be
invoked by calling the gss_wrap
routine
False - No confidentiality service (via
gss_wrap) available. gss_wrap will
provide message encapsulation,
data-origin authentication and
integrity services only.
GSS_C_INTEG_FLAG
True - Integrity service may be invoked by
calling either gss_get_mic or
gss_wrap routines.
False - Per-message integrity service
unavailable.
GSS_C_ANON_FLAG
True - The initiator does not wish to
be authenticated; the src_name
parameter (if requested) contains
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an anonymous internal name.
False - The initiator has been
authenticated normally.
GSS_C_PROT_READY_FLAG
True - Protection services (as specified
by the states of the GSS_C_CONF_FLAG
and GSS_C_INTEG_FLAG) are available
if the accompanying major status
return value is either GSS_S_COMPLETE
or GSS_S_CONTINUE_NEEDED.
False - Protection services (as specified
by the states of the GSS_C_CONF_FLAG
and GSS_C_INTEG_FLAG) are available
only if the accompanying major status
return value is GSS_S_COMPLETE.
GSS_C_TRANS_FLAG
True - The resultant security context may
be transferred to other processes via
a call to gss_export_sec_context().
False - The security context is not
transferable.
All other bits should be set to zero.
time_rec Integer, modify, optional
number of seconds for which the context will
remain valid. Specify NULL if not required.
delegated_cred_handle
gss_cred_id_t, modify, optional credential
handle for credentials received from context
initiator. Only valid if deleg_flag in
ret_flags is true, in which case an explicit
credential handle (i.e. not GSS_C_NO_CREDENTIAL)
will be returned; if deleg_flag is false,
gss_accept_context() will set this parameter to
GSS_C_NO_CREDENTIAL. If a credential handle is
returned, the associated resources must be
released by the application after use with a
call to gss_release_cred(). Specify NULL if not
required.
minor_status Integer, modify
Mechanism specific status code.
GSS_S_CONTINUE_NEEDED Indicates that a token from the peer
application is required to complete the
context, and that gss_accept_sec_context must
be called again with that token.
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GSS_S_DEFECTIVE_TOKEN Indicates that consistency checks performed on
the input_token failed.
GSS_S_DEFECTIVE_CREDENTIAL Indicates that consistency checks
performed on the credential failed.
GSS_S_NO_CRED The supplied credentials were not valid for context
acceptance, or the credential handle did not
reference any credentials.
GSS_S_CREDENTIALS_EXPIRED The referenced credentials have expired.
GSS_S_BAD_BINDINGS The input_token contains different channel
bindings to those specified via the
input_chan_bindings parameter.
GSS_S_NO_CONTEXT Indicates that the supplied context handle did not
refer to a valid context.
GSS_S_BAD_SIG The input_token contains an invalid MIC.
GSS_S_OLD_TOKEN The input_token was too old. This is a fatal error
during context establishment.
GSS_S_DUPLICATE_TOKEN The input_token is valid, but is a duplicate of
a token already processed. This is a fatal
error during context establishment.
GSS_S_BAD_MECH The received token specified a mechanism that is
not supported by the implementation or the
provided credential.
5.2. gss_acquire_cred
OM_uint32 gss_acquire_cred (
OM_uint32 *minor_status,
const gss_name_t desired_name,
OM_uint32 time_req,
const gss_OID_set desired_mechs,
gss_cred_usage_t cred_usage,
gss_cred_id_t *output_cred_handle,
gss_OID_set *actual_mechs,
OM_uint32 *time_rec)
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Purpose:
Allows an application to acquire a handle for a pre-existing
credential by name. GSS-API implementations must impose a local
access-control policy on callers of this routine to prevent
unauthorized callers from acquiring credentials to which they are not
entitled. This routine is not intended to provide a "login to the
network" function, as such a function would involve the creation of
new credentials rather than merely acquiring a handle to existing
credentials. Such functions, if required, should be defined in
implementation-specific extensions to the API.
If desired_name is GSS_C_NO_NAME, the call is interpreted as a
request for a credential handle that will invoke default behavior
when passed to gss_init_sec_context() (if cred_usage is
GSS_C_INITIATE or GSS_C_BOTH) or gss_accept_sec_context() (if
cred_usage is GSS_C_ACCEPT or GSS_C_BOTH).
Mechanisms should honor the desired_mechs parameter, and return a
credential that is suitable to use only with the requested
mechanisms. An exception to this is the case where one underlying
credential element can be shared by multiple mechanisms; in this case
it is permissible for an implementation to indicate all mechanisms
with which the credential element may be used. If desired_mechs is
an empty set, behavior is undefined.
This routine is expected to be used primarily by context acceptors,
since implementations are likely to provide mechanism-specific ways
of obtaining GSS-API initiator credentials from the system login
process. Some implementations may therefore not support the
acquisition of GSS_C_INITIATE or GSS_C_BOTH credentials via
gss_acquire_cred for any name other than GSS_C_NO_NAME, or a name
produced by applying either gss_inquire_cred to a valid credential,
or gss_inquire_context to an active context.
If credential acquisition is time-consuming for a mechanism, the
mechanism may choose to delay the actual acquisition until the
credential is required (e.g. by gss_init_sec_context or
gss_accept_sec_context). Such mechanism-specific implementation
decisions should be invisible to the calling application; thus a call
of gss_inquire_cred immediately following the call of
gss_acquire_cred must return valid credential data, and may therefore
incur the overhead of a deferred credential acquisition.
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Parameters:
desired_name gss_name_t, read
Name of principal whose credential
should be acquired
time_req Integer, read, optional
number of seconds that credentials
should remain valid. Specify GSS_C_INDEFINITE
to request that the credentials have the maximum
permitted lifetime.
desired_mechs Set of Object IDs, read, optional
set of underlying security mechanisms that
may be used. GSS_C_NO_OID_SET may be used
to obtain an implementation-specific default.
cred_usage gss_cred_usage_t, read
GSS_C_BOTH - Credentials may be used
either to initiate or accept
security contexts.
GSS_C_INITIATE - Credentials will only be
used to initiate security contexts.
GSS_C_ACCEPT - Credentials will only be used to
accept security contexts.
output_cred_handle gss_cred_id_t, modify
The returned credential handle. Resources
associated with this credential handle must
be released by the application after use
with a call to gss_release_cred().
actual_mechs Set of Object IDs, modify, optional
The set of mechanisms for which the
credential is valid. Storage associated
with the returned OID-set must be released by
the application after use with a call to
gss_release_oid_set(). Specify NULL if not
required.
time_rec Integer, modify, optional
Actual number of seconds for which the
returned credentials will remain valid. If the
implementation does not support expiration of
credentials, the value GSS_C_INDEFINITE will
be returned. Specify NULL if not required
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minor_status Integer, modify
Mechanism specific status code.
Function value: GSS status code
GSS_S_COMPLETE Successful completion
GSS_S_BAD_MECH Unavailable mechanism requested
GSS_S_BAD_NAMETYPE Type contained within desired_name parameter
is not supported
GSS_S_BAD_NAME Value supplied for desired_name parameter is ill
formed.
GSS_S_CREDENTIALS_EXPIRED The credentials could not be acquired
Because they have expired.
GSS_S_NO_CRED No credentials were found for the specified name.
5.3. gss_add_cred
OM_uint32 gss_add_cred (
OM_uint32 *minor_status,
const gss_cred_id_t input_cred_handle,
const gss_name_t desired_name,
const gss_OID desired_mech,
gss_cred_usage_t cred_usage,
OM_uint32 initiator_time_req,
OM_uint32 acceptor_time_req,
gss_cred_id_t *output_cred_handle,
gss_OID_set *actual_mechs,
OM_uint32 *initiator_time_rec,
OM_uint32 *acceptor_time_rec)
Purpose:
Adds a credential-element to a credential. The credential-element is
identified by the name of the principal to which it refers. GSS-API
implementations must impose a local access-control policy on callers
of this routine to prevent unauthorized callers from acquiring
credential-elements to which they are not entitled. This routine is
not intended to provide a "login to the network" function, as such a
function would involve the creation of new mechanism-specific
authentication data, rather than merely acquiring a GSS-API handle to
existing data. Such functions, if required, should be defined in
implementation-specific extensions to the API.
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If desired_name is GSS_C_NO_NAME, the call is interpreted as a
request to add a credential element that will invoke default behavior
when passed to gss_init_sec_context() (if cred_usage is
GSS_C_INITIATE or GSS_C_BOTH) or gss_accept_sec_context() (if
cred_usage is GSS_C_ACCEPT or GSS_C_BOTH).
This routine is expected to be used primarily by context acceptors,
since implementations are likely to provide mechanism-specific ways
of obtaining GSS-API initiator credentials from the system login
process. Some implementations may therefore not support the
acquisition of GSS_C_INITIATE or GSS_C_BOTH credentials via
gss_acquire_cred for any name other than GSS_C_NO_NAME, or a name
produced by applying either gss_inquire_cred to a valid credential,
or gss_inquire_context to an active context.
If credential acquisition is time-consuming for a mechanism, the
mechanism may choose to delay the actual acquisition until the
credential is required (e.g. by gss_init_sec_context or
gss_accept_sec_context). Such mechanism-specific implementation
decisions should be invisible to the calling application; thus a call
of gss_inquire_cred immediately following the call of gss_add_cred
must return valid credential data, and may therefore incur the
overhead of a deferred credential acquisition.
This routine can be used to either compose a new credential
containing all credential-elements of the original in addition to the
newly-acquire credential-element, or to add the new credential-
element to an existing credential. If NULL is specified for the
output_cred_handle parameter argument, the new credential-element
will be added to the credential identified by input_cred_handle; if a
valid pointer is specified for the output_cred_handle parameter, a
new credential handle will be created.
If GSS_C_NO_CREDENTIAL is specified as the input_cred_handle,
gss_add_cred will compose a credential (and set the
output_cred_handle parameter accordingly) based on default behavior.
That is, the call will have the same effect as if the application had
first made a call to gss_acquire_cred(), specifying the same usage
and passing GSS_C_NO_NAME as the desired_name parameter to obtain an
explicit credential handle embodying default behavior, passed this
credential handle to gss_add_cred(), and finally called
gss_release_cred() on the first credential handle.
If GSS_C_NO_CREDENTIAL is specified as the input_cred_handle
parameter, a non-NULL output_cred_handle must be supplied.
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Parameters:
minor_status Integer, modify
Mechanism specific status code.
input_cred_handle gss_cred_id_t, read, optional
The credential to which a credential-element
will be added. If GSS_C_NO_CREDENTIAL is
specified, the routine will compose the new
credential based on default behavior (see
description above). Note that, while the
credential-handle is not modified by
gss_add_cred(), the underlying credential
will be modified if output_credential_handle
is NULL.
desired_name gss_name_t, read.
Name of principal whose credential
should be acquired.
desired_mech Object ID, read
Underlying security mechanism with which the
credential may be used.
cred_usage gss_cred_usage_t, read
GSS_C_BOTH - Credential may be used
either to initiate or accept
security contexts.
GSS_C_INITIATE - Credential will only be
used to initiate security
contexts.
GSS_C_ACCEPT - Credential will only be used to
accept security contexts.
initiator_time_req Integer, read, optional
number of seconds that the credential
should remain valid for initiating security
contexts. This argument is ignored if the
composed credentials are of type GSS_C_ACCEPT.
Specify GSS_C_INDEFINITE to request that the
credentials have the maximum permitted
initiator lifetime.
acceptor_time_req Integer, read, optional
number of seconds that the credential
should remain valid for accepting security
contexts. This argument is ignored if the
composed credentials are of type GSS_C_INITIATE.
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Specify GSS_C_INDEFINITE to request that the
credentials have the maximum permitted initiator
lifetime.
output_cred_handle gss_cred_id_t, modify, optional
The returned credential handle, containing
the new credential-element and all the
credential-elements from input_cred_handle.
If a valid pointer to a gss_cred_id_t is
supplied for this parameter, gss_add_cred
creates a new credential handle containing all
credential-elements from the input_cred_handle
and the newly acquired credential-element; if
NULL is specified for this parameter, the newly
acquired credential-element will be added
to the credential identified by input_cred_handle.
The resources associated with any credential
handle returned via this parameter must be
released by the application after use with a
call to gss_release_cred().
actual_mechs Set of Object IDs, modify, optional
The complete set of mechanisms for which
the new credential is valid. Storage for
the returned OID-set must be freed by the
application after use with a call to
gss_release_oid_set(). Specify NULL if
not required.
initiator_time_rec Integer, modify, optional
Actual number of seconds for which the
returned credentials will remain valid for
initiating contexts using the specified
mechanism. If the implementation or mechanism
does not support expiration of credentials, the
value GSS_C_INDEFINITE will be returned. Specify
NULL if not required
acceptor_time_rec Integer, modify, optional
Actual number of seconds for which the
returned credentials will remain valid for
accepting security contexts using the specified
mechanism. If the implementation or mechanism
does not support expiration of credentials, the
value GSS_C_INDEFINITE will be returned. Specify
NULL if not required
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Function value: GSS status code
GSS_S_COMPLETE Successful completion
GSS_S_BAD_MECH Unavailable mechanism requested
GSS_S_BAD_NAMETYPE Type contained within desired_name parameter
is not supported
GSS_S_BAD_NAME Value supplied for desired_name parameter is
ill-formed.
GSS_S_DUPLICATE_ELEMENT The credential already contains an element
for the requested mechanism with overlapping
usage and validity period.
GSS_S_CREDENTIALS_EXPIRED The required credentials could not be
added because they have expired.
GSS_S_NO_CRED No credentials were found for the specified name.
5.4. gss_add_oid_set_member
OM_uint32 gss_add_oid_set_member (
OM_uint32 *minor_status,
const gss_OID member_oid,
gss_OID_set *oid_set)
Purpose:
Add an Object Identifier to an Object Identifier set. This routine
is intended for use in conjunction with gss_create_empty_oid_set when
constructing a set of mechanism OIDs for input to gss_acquire_cred.
The oid_set parameter must refer to an OID-set that was created by
GSS-API (e.g. a set returned by gss_create_empty_oid_set()). GSS-API
creates a copy of the member_oid and inserts this copy into the set,
expanding the storage allocated to the OID-set's elements array if
necessary. The routine may add the new member OID anywhere within
the elements array, and implementations should verify that the new
member_oid is not already contained within the elements array; if the
member_oid is already present, the oid_set should remain unchanged.
Parameters:
minor_status Integer, modify
Mechanism specific status code
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member_oid Object ID, read
The object identifier to copied into
the set.
oid_set Set of Object ID, modify
The set in which the object identifier
should be inserted.
Function value: GSS status code
GSS_S_COMPLETE Successful completion
5.5. gss_canonicalize_name
OM_uint32 gss_canonicalize_name (
OM_uint32 *minor_status,
const gss_name_t input_name,
const gss_OID mech_type,
gss_name_t *output_name)
Purpose:
Generate a canonical mechanism name (MN) from an arbitrary internal
name. The mechanism name is the name that would be returned to a
context acceptor on successful authentication of a context where the
initiator used the input_name in a successful call to
gss_acquire_cred, specifying an OID set containing as its
only member, followed by a call to gss_init_sec_context, specifying
as the authentication mechanism.
Parameters:
minor_status Integer, modify
Mechanism specific status code
input_name gss_name_t, read
The name for which a canonical form is
desired
mech_type Object ID, read
The authentication mechanism for which the
canonical form of the name is desired. The
desired mechanism must be specified explicitly;
no default is provided.
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output_name gss_name_t, modify
The resultant canonical name. Storage
associated with this name must be freed by
the application after use with a call to
gss_release_name().
Function value: GSS status code
GSS_S_COMPLETE Successful completion.
GSS_S_BAD_MECH The identified mechanism is not supported.
GSS_S_BAD_NAMETYPE The provided internal name contains no elements
that could be processed by the specified
mechanism.
GSS_S_BAD_NAME The provided internal name was ill-formed.
5.6. gss_compare_name
OM_uint32 gss_compare_name (
OM_uint32 *minor_status,
const gss_name_t name1,
const gss_name_t name2,
int *name_equal)
Purpose:
Allows an application to compare two internal-form names to determine
whether they refer to the same entity.
If either name presented to gss_compare_name denotes an anonymous
principal, the routines should indicate that the two names do not
refer to the same identity.
Parameters:
minor_status Integer, modify
Mechanism specific status code.
name1 gss_name_t, read
internal-form name
name2 gss_name_t, read
internal-form name
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name_equal boolean, modify
non-zero - names refer to same entity
zero - names refer to different entities
(strictly, the names are not known
to refer to the same identity).
Function value: GSS status code
GSS_S_COMPLETE Successful completion
GSS_S_BAD_NAMETYPE The two names were of incomparable types.
GSS_S_BAD_NAME One or both of name1 or name2 was ill-formed.
5.7. gss_context_time
OM_uint32 gss_context_time (
OM_uint32 *minor_status,
const gss_ctx_id_t context_handle,
OM_uint32 *time_rec)
Purpose:
Determines the number of seconds for which the specified context will
remain valid.
Parameters:
minor_status Integer, modify
Implementation specific status code.
context_handle gss_ctx_id_t, read
Identifies the context to be interrogated.
time_rec Integer, modify
Number of seconds that the context will remain
valid. If the context has already expired,
zero will be returned.
Function value: GSS status code
GSS_S_COMPLETE Successful completion
GSS_S_CONTEXT_EXPIRED The context has already expired
GSS_S_NO_CONTEXT The context_handle parameter did not identify
a valid context
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5.8. gss_create_empty_oid_set
OM_uint32 gss_create_empty_oid_set (
OM_uint32 *minor_status,
gss_OID_set *oid_set)
Purpose:
Create an object-identifier set containing no object identifiers, to
which members may be subsequently added using the
gss_add_oid_set_member() routine. These routines are intended to be
used to construct sets of mechanism object identifiers, for input to
gss_acquire_cred.
Parameters:
minor_status Integer, modify
Mechanism specific status code
oid_set Set of Object IDs, modify
The empty object identifier set.
The routine will allocate the
gss_OID_set_desc object, which the
application must free after use with
a call to gss_release_oid_set().
Function value: GSS status code
GSS_S_COMPLETE Successful completion
5.9. gss_delete_sec_context
OM_uint32 gss_delete_sec_context (
OM_uint32 *minor_status,
gss_ctx_id_t *context_handle,
gss_buffer_t output_token)
Purpose:
Delete a security context. gss_delete_sec_context will delete the
local data structures associated with the specified security context,
and may generate an output_token, which when passed to the peer
gss_process_context_token will instruct it to do likewise. If no
token is required by the mechanism, the GSS-API should set the length
field of the output_token (if provided) to zero. No further security
services may be obtained using the context specified by
context_handle.
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In addition to deleting established security contexts,
gss_delete_sec_context must also be able to delete "half-built"
security contexts resulting from an incomplete sequence of
gss_init_sec_context()/gss_accept_sec_context() calls.
The output_token parameter is retained for compatibility with version
1 of the GSS-API. It is recommended that both peer applications
invoke gss_delete_sec_context passing the value GSS_C_NO_BUFFER for
the output_token parameter, indicating that no token is required, and
that gss_delete_sec_context should simply delete local context data
structures. If the application does pass a valid buffer to
gss_delete_sec_context, mechanisms are encouraged to return a zero-
length token, indicating that no peer action is necessary, and that
no token should be transferred by the application.
Parameters:
minor_status Integer, modify
Mechanism specific status code.
context_handle gss_ctx_id_t, modify
context handle identifying context to delete.
After deleting the context, the GSS-API will set
this context handle to GSS_C_NO_CONTEXT.
output_token buffer, opaque, modify, optional
token to be sent to remote application to
instruct it to also delete the context. It
is recommended that applications specify
GSS_C_NO_BUFFER for this parameter, requesting
local deletion only. If a buffer parameter is
provided by the application, the mechanism may
return a token in it; mechanisms that implement
only local deletion should set the length field of
this token to zero to indicate to the application
that no token is to be sent to the peer.
Function value: GSS status code
GSS_S_COMPLETE Successful completion
GSS_S_NO_CONTEXT No valid context was supplied
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5.10.gss_display_name
OM_uint32 gss_display_name (
OM_uint32 *minor_status,
const gss_name_t input_name,
gss_buffer_t output_name_buffer,
gss_OID *output_name_type)
Purpose:
Allows an application to obtain a textual representation of an opaque
internal-form name for display purposes. The syntax of a printable
name is defined by the GSS-API implementation.
If input_name denotes an anonymous principal, the implementation
should return the gss_OID value GSS_C_NT_ANONYMOUS as the
output_name_type, and a textual name that is syntactically distinct
from all valid supported printable names in output_name_buffer.
If input_name was created by a call to gss_import_name, specifying
GSS_C_NO_OID as the name-type, implementations that employ lazy
conversion between name types may return GSS_C_NO_OID via the
output_name_type parameter.
Parameters:
minor_status Integer, modify
Mechanism specific status code.
input_name gss_name_t, read
name to be displayed
output_name_buffer buffer, character-string, modify
buffer to receive textual name string.
The application must free storage associated
with this name after use with a call to
gss_release_buffer().
output_name_type Object ID, modify, optional
The type of the returned name. The returned
gss_OID will be a pointer into static storage,
and should be treated as read-only by the caller
(in particular, the application should not attempt
to free it). Specify NULL if not required.
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Function value: GSS status code
GSS_S_COMPLETE Successful completion
GSS_S_BAD_NAME input_name was ill-formed
5.11.gss_display_status
OM_uint32 gss_display_status (
OM_uint32 *minor_status,
OM_uint32 status_value,
int status_type,
const gss_OID mech_type,
OM_uint32 *message_context,
gss_buffer_t status_string)
Purpose:
Allows an application to obtain a textual representation of a GSS-API
status code, for display to the user or for logging purposes. Since
some status values may indicate multiple conditions, applications may
need to call gss_display_status multiple times, each call generating
a single text string. The message_context parameter is used by
gss_display_status to store state information about which error
messages have already been extracted from a given status_value;
message_context must be initialized to 0 by the application prior to
the first call, and gss_display_status will return a non-zero value
in this parameter if there are further messages to extract.
The message_context parameter contains all state information required
by gss_display_status in order to extract further messages from the
status_value; even when a non-zero value is returned in this
parameter, the application is not required to call gss_display_status
again unless subsequent messages are desired. The following code
extracts all messages from a given status code and prints them to
stderr:
OM_uint32 message_context;
OM_uint32 status_code;
OM_uint32 maj_status;
OM_uint32 min_status;
gss_buffer_desc status_string;
...
message_context = 0;
do {
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maj_status = gss_display_status (
&min_status,
status_code,
GSS_C_GSS_CODE,
GSS_C_NO_OID,
&message_context,
&status_string)
fprintf(stderr,
"%.*s\n",
(int)status_string.length,
(char *)status_string.value);
gss_release_buffer(&min_status, &status_string);
} while (message_context != 0);
Parameters:
minor_status Integer, modify
Mechanism specific status code.
status_value Integer, read
Status value to be converted
status_type Integer, read
GSS_C_GSS_CODE - status_value is a GSS status
code
GSS_C_MECH_CODE - status_value is a mechanism
status code
mech_type Object ID, read, optional
Underlying mechanism (used to interpret a
minor status value) Supply GSS_C_NO_OID to
obtain the system default.
message_context Integer, read/modify
Should be initialized to zero by the
application prior to the first call.
On return from gss_display_status(),
a non-zero status_value parameter indicates
that additional messages may be extracted
from the status code via subsequent calls
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to gss_display_status(), passing the same
status_value, status_type, mech_type, and
message_context parameters.
status_string buffer, character string, modify
textual interpretation of the status_value.
Storage associated with this parameter must
be freed by the application after use with
a call to gss_release_buffer().
Function value: GSS status code
GSS_S_COMPLETE Successful completion
GSS_S_BAD_MECH Indicates that translation in accordance with
an unsupported mechanism type was requested
GSS_S_BAD_STATUS The status value was not recognized, or the
status type was neither GSS_C_GSS_CODE nor
GSS_C_MECH_CODE.
5.12. gss_duplicate_name
OM_uint32 gss_duplicate_name (
OM_uint32 *minor_status,
const gss_name_t src_name,
gss_name_t *dest_name)
Purpose:
Create an exact duplicate of the existing internal name src_name.
The new dest_name will be independent of src_name (i.e. src_name and
dest_name must both be released, and the release of one shall not
affect the validity of the other).
Parameters:
minor_status Integer, modify
Mechanism specific status code.
src_name gss_name_t, read
internal name to be duplicated.
dest_name gss_name_t, modify
The resultant copy of .
Storage associated with this name must
be freed by the application after use
with a call to gss_release_name().
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Function value: GSS status code
GSS_S_COMPLETE Successful completion
GSS_S_BAD_NAME The src_name parameter was ill-formed.
5.13. gss_export_name
OM_uint32 gss_export_name (
OM_uint32 *minor_status,
const gss_name_t input_name,
gss_buffer_t exported_name)
Purpose:
To produce a canonical contiguous string representation of a
mechanism name (MN), suitable for direct comparison (e.g. with
memcmp) for use in authorization functions (e.g. matching entries in
an access-control list). The parameter must specify a
valid MN (i.e. an internal name generated by gss_accept_sec_context
or by gss_canonicalize_name).
Parameters:
minor_status Integer, modify
Mechanism specific status code
input_name gss_name_t, read
The MN to be exported
exported_name gss_buffer_t, octet-string, modify
The canonical contiguous string form of
. Storage associated with
this string must freed by the application
after use with gss_release_buffer().
Function value: GSS status code
GSS_S_COMPLETE Successful completion
GSS_S_NAME_NOT_MN The provided internal name was not a mechanism
name.
GSS_S_BAD_NAME The provided internal name was ill-formed.
GSS_S_BAD_NAMETYPE The internal name was of a type not supported
by the GSS-API implementation.
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5.14. gss_export_sec_context
OM_uint32 gss_export_sec_context (
OM_uint32 *minor_status,
gss_ctx_id_t *context_handle,
gss_buffer_t interprocess_token)
Purpose:
Provided to support the sharing of work between multiple processes.
This routine will typically be used by the context-acceptor, in an
application where a single process receives incoming connection
requests and accepts security contexts over them, then passes the
established context to one or more other processes for message
exchange. gss_export_sec_context() deactivates the security context
for the calling process and creates an interprocess token which, when
passed to gss_import_sec_context in another process, will re-activate
the context in the second process. Only a single instantiation of a
given context may be active at any one time; a subsequent attempt by
a context exporter to access the exported security context will fail.
The implementation may constrain the set of processes by which the
interprocess token may be imported, either as a function of local
security policy, or as a result of implementation decisions. For
example, some implementations may constrain contexts to be passed
only between processes that run under the same account, or which are
part of the same process group.
The interprocess token may contain security-sensitive information
(for example cryptographic keys). While mechanisms are encouraged to
either avoid placing such sensitive information within interprocess
tokens, or to encrypt the token before returning it to the
application, in a typical object-library GSS-API implementation this
may not be possible. Thus the application must take care to protect
the interprocess token, and ensure that any process to which the
token is transferred is trustworthy.
If creation of the interprocess token is successful, the
implementation shall deallocate all process-wide resources associated
with the security context, and set the context_handle to
GSS_C_NO_CONTEXT. In the event of an error that makes it impossible
to complete the export of the security context, the implementation
must not return an interprocess token, and should strive to leave the
security context referenced by the context_handle parameter
untouched. If this is impossible, it is permissible for the
implementation to delete the security context, providing it also sets
the context_handle parameter to GSS_C_NO_CONTEXT.
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Parameters:
minor_status Integer, modify
Mechanism specific status code
context_handle gss_ctx_id_t, modify
context handle identifying the context to
transfer.
interprocess_token buffer, opaque, modify
token to be transferred to target process.
Storage associated with this token must be
freed by the application after use with a
call to gss_release_buffer().
Function value: GSS status code
GSS_S_COMPLETE Successful completion
GSS_S_CONTEXT_EXPIRED The context has expired
GSS_S_NO_CONTEXT The context was invalid
GSS_S_UNAVAILABLE The operation is not supported.
5.15. gss_get_mic
OM_uint32 gss_get_mic (
OM_uint32 *minor_status,
const gss_ctx_id_t context_handle,
gss_qop_t qop_req,
const gss_buffer_t message_buffer,
gss_buffer_t msg_token)
Purpose:
Generates a cryptographic MIC for the supplied message, and places
the MIC in a token for transfer to the peer application. The qop_req
parameter allows a choice between several cryptographic algorithms,
if supported by the chosen mechanism.
Since some application-level protocols may wish to use tokens emitted
by gss_wrap() to provide "secure framing", implementations must
support derivation of MICs from zero-length messages.
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Parameters:
minor_status Integer, modify
Implementation specific status code.
context_handle gss_ctx_id_t, read
identifies the context on which the message
will be sent
qop_req gss_qop_t, read, optional
Specifies requested quality of protection.
Callers are encouraged, on portability grounds,
to accept the default quality of protection
offered by the chosen mechanism, which may be
requested by specifying GSS_C_QOP_DEFAULT for
this parameter. If an unsupported protection
strength is requested, gss_get_mic will return a
major_status of GSS_S_BAD_QOP.
message_buffer buffer, opaque, read
message to be protected
msg_token buffer, opaque, modify
buffer to receive token. The application must
free storage associated with this buffer after
use with a call to gss_release_buffer().
Function value: GSS status code
GSS_S_COMPLETE Successful completion
GSS_S_CONTEXT_EXPIRED The context has already expired
GSS_S_NO_CONTEXT The context_handle parameter did not identify
a valid context
GSS_S_BAD_QOP The specified QOP is not supported by the
mechanism.
5.16. gss_import_name
OM_uint32 gss_import_name (
OM_uint32 *minor_status,
const gss_buffer_t input_name_buffer,
const gss_OID input_name_type,
gss_name_t *output_name)
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Purpose:
Convert a contiguous string name to internal form. In general, the
internal name returned (via the parameter) will not be
an MN; the exception to this is if the indicates
that the contiguous string provided via the
parameter is of type GSS_C_NT_EXPORT_NAME, in which case the returned
internal name will be an MN for the mechanism that exported the name.
Parameters:
minor_status Integer, modify
Mechanism specific status code
input_name_buffer buffer, octet-string, read
buffer containing contiguous string name to convert
input_name_type Object ID, read, optional
Object ID specifying type of printable
name. Applications may specify either
GSS_C_NO_OID to use a mechanism-specific
default printable syntax, or an OID recognized
by the GSS-API implementation to name a
specific namespace.
output_name gss_name_t, modify
returned name in internal form. Storage
associated with this name must be freed
by the application after use with a call
to gss_release_name().
Function value: GSS status code
GSS_S_COMPLETE Successful completion
GSS_S_BAD_NAMETYPE The input_name_type was unrecognized
GSS_S_BAD_NAME The input_name parameter could not be interpreted
as a name of the specified type
GSS_S_BAD_MECH The input name-type was GSS_C_NT_EXPORT_NAME,
but the mechanism contained within the
input-name is not supported
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5.17. gss_import_sec_context
OM_uint32 gss_import_sec_context (
OM_uint32 *minor_status,
const gss_buffer_t interprocess_token,
gss_ctx_id_t *context_handle)
Purpose:
Allows a process to import a security context established by another
process. A given interprocess token may be imported only once. See
gss_export_sec_context.
Parameters:
minor_status Integer, modify
Mechanism specific status code
interprocess_token buffer, opaque, modify
token received from exporting process
context_handle gss_ctx_id_t, modify
context handle of newly reactivated context.
Resources associated with this context handle
must be released by the application after use
with a call to gss_delete_sec_context().
Function value: GSS status code
GSS_S_COMPLETE Successful completion.
GSS_S_NO_CONTEXT The token did not contain a valid context
reference.
GSS_S_DEFECTIVE_TOKEN The token was invalid.
GSS_S_UNAVAILABLE The operation is unavailable.
GSS_S_UNAUTHORIZED Local policy prevents the import of this context
by the current process.
5.18. gss_indicate_mechs
OM_uint32 gss_indicate_mechs (
OM_uint32 *minor_status,
gss_OID_set *mech_set)
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Purpose:
Allows an application to determine which underlying security
mechanisms are available.
Parameters:
minor_status Integer, modify
Mechanism specific status code.
mech_set set of Object IDs, modify
set of implementation-supported mechanisms.
The returned gss_OID_set value will be a
dynamically-allocated OID set, that should
be released by the caller after use with a
call to gss_release_oid_set().
Function value: GSS status code
GSS_S_COMPLETE Successful completion
5.19. gss_init_sec_context
OM_uint32 gss_init_sec_context (
OM_uint32 *minor_status,
const gss_cred_id_t initiator_cred_handle,
gss_ctx_id_t *context_handle,\
const gss_name_t target_name,
const gss_OID mech_type,
OM_uint32 req_flags,
OM_uint32 time_req,
const gss_channel_bindings_t input_chan_bindings,
const gss_buffer_t input_token
gss_OID *actual_mech_type,
gss_buffer_t output_token,
OM_uint32 *ret_flags,
OM_uint32 *time_rec )
Purpose:
Initiates the establishment of a security context between the
application and a remote peer. Initially, the input_token parameter
should be specified either as GSS_C_NO_BUFFER, or as a pointer to a
gss_buffer_desc object whose length field contains the value zero.
The routine may return a output_token which should be transferred to
the peer application, where the peer application will present it to
gss_accept_sec_context. If no token need be sent,
gss_init_sec_context will indicate this by setting the length field
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of the output_token argument to zero. To complete the context
establishment, one or more reply tokens may be required from the peer
application; if so, gss_init_sec_context will return a status
containing the supplementary information bit GSS_S_CONTINUE_NEEDED.
In this case, gss_init_sec_context should be called again when the
reply token is received from the peer application, passing the reply
token to gss_init_sec_context via the input_token parameters.
Portable applications should be constructed to use the token length
and return status to determine whether a token needs to be sent or
waited for. Thus a typical portable caller should always invoke
gss_init_sec_context within a loop:
int context_established = 0;
gss_ctx_id_t context_hdl = GSS_C_NO_CONTEXT;
...
input_token->length = 0;
while (!context_established) {
maj_stat = gss_init_sec_context(&min_stat,
cred_hdl,
&context_hdl,
target_name,
desired_mech,
desired_services,
desired_time,
input_bindings,
input_token,
&actual_mech,
output_token,
&actual_services,
&actual_time);
if (GSS_ERROR(maj_stat)) {
report_error(maj_stat, min_stat);
};
if (output_token->length != 0) {
send_token_to_peer(output_token);
gss_release_buffer(&min_stat, output_token)
};
if (GSS_ERROR(maj_stat)) {
if (context_hdl != GSS_C_NO_CONTEXT)
gss_delete_sec_context(&min_stat,
&context_hdl,
GSS_C_NO_BUFFER);
break;
};
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if (maj_stat & GSS_S_CONTINUE_NEEDED) {
receive_token_from_peer(input_token);
} else {
context_established = 1;
};
};
Whenever the routine returns a major status that includes the value
GSS_S_CONTINUE_NEEDED, the context is not fully established and the
following restrictions apply to the output parameters:
The value returned via the time_rec parameter is undefined Unless
the accompanying ret_flags parameter contains the bit
GSS_C_PROT_READY_FLAG, indicating that per-message services may be
applied in advance of a successful completion status, the value
returned via the actual_mech_type parameter is undefined until the
routine returns a major status value of GSS_S_COMPLETE.
The values of the GSS_C_DELEG_FLAG, GSS_C_MUTUAL_FLAG,
GSS_C_REPLAY_FLAG, GSS_C_SEQUENCE_FLAG, GSS_C_CONF_FLAG,
GSS_C_INTEG_FLAG and GSS_C_ANON_FLAG bits returned via the
ret_flags parameter should contain the values that the
implementation expects would be valid if context establishment
were to succeed. In particular, if the application has requested
a service such as delegation or anonymous authentication via the
req_flags argument, and such a service is unavailable from the
underlying mechanism, gss_init_sec_context should generate a token
that will not provide the service, and indicate via the ret_flags
argument that the service will not be supported. The application
may choose to abort the context establishment by calling
gss_delete_sec_context (if it cannot continue in the absence of
the service), or it may choose to transmit the token and continue
context establishment (if the service was merely desired but not
mandatory).
The values of the GSS_C_PROT_READY_FLAG and GSS_C_TRANS_FLAG bits
within ret_flags should indicate the actual state at the time
gss_init_sec_context returns, whether or not the context is fully
established.
GSS-API implementations that support per-message protection are
encouraged to set the GSS_C_PROT_READY_FLAG in the final ret_flags
returned to a caller (i.e. when accompanied by a GSS_S_COMPLETE
status code). However, applications should not rely on this
behavior as the flag was not defined in Version 1 of the GSS-API.
Instead, applications should determine what per-message services
are available after a successful context establishment according
to the GSS_C_INTEG_FLAG and GSS_C_CONF_FLAG values.
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All other bits within the ret_flags argument should be set to
zero.
If the initial call of gss_init_sec_context() fails, the
implementation should not create a context object, and should leave
the value of the context_handle parameter set to GSS_C_NO_CONTEXT to
indicate this. In the event of a failure on a subsequent call, the
implementation is permitted to delete the "half-built" security
context (in which case it should set the context_handle parameter to
GSS_C_NO_CONTEXT), but the preferred behavior is to leave the
security context untouched for the application to delete (using
gss_delete_sec_context).
During context establishment, the informational status bits
GSS_S_OLD_TOKEN and GSS_S_DUPLICATE_TOKEN indicate fatal errors, and
GSS-API mechanisms should always return them in association with a
routine error of GSS_S_FAILURE. This requirement for pairing did not
exist in version 1 of the GSS-API specification, so applications that
wish to run over version 1 implementations must special-case these
codes.
Parameters:
minor_status Integer, modify
Mechanism specific status code.
initiator_cred_handle gss_cred_id_t, read, optional
handle for credentials claimed. Supply
GSS_C_NO_CREDENTIAL to act as a default
initiator principal. If no default
initiator is defined, the function will
return GSS_S_NO_CRED.
context_handle gss_ctx_id_t, read/modify
context handle for new context. Supply
GSS_C_NO_CONTEXT for first call; use value
returned by first call in continuation calls.
Resources associated with this context-handle
must be released by the application after use
with a call to gss_delete_sec_context().
target_name gss_name_t, read
Name of target
mech_type OID, read, optional
Object ID of desired mechanism. Supply
GSS_C_NO_OID to obtain an implementation
specific default
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req_flags bit-mask, read
Contains various independent flags, each of
which requests that the context support a
specific service option. Symbolic
names are provided for each flag, and the
symbolic names corresponding to the required
flags should be logically-ORed
together to form the bit-mask value. The
flags are:
GSS_C_DELEG_FLAG
True - Delegate credentials to remote peer
False - Don't delegate
GSS_C_MUTUAL_FLAG
True - Request that remote peer
authenticate itself
False - Authenticate self to remote peer
only
GSS_C_REPLAY_FLAG
True - Enable replay detection for
messages protected with gss_wrap
or gss_get_mic
False - Don't attempt to detect
replayed messages
GSS_C_SEQUENCE_FLAG
True - Enable detection of out-of-sequence
protected messages
False - Don't attempt to detect
out-of-sequence messages
GSS_C_CONF_FLAG
True - Request that confidentiality service
be made available (via gss_wrap)
False - No per-message confidentiality service
is required.
GSS_C_INTEG_FLAG
True - Request that integrity service be
made available (via gss_wrap or
gss_get_mic)
False - No per-message integrity service
is required.
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GSS_C_ANON_FLAG
True - Do not reveal the initiator's
identity to the acceptor.
False - Authenticate normally.
time_req Integer, read, optional
Desired number of seconds for which context
should remain valid. Supply 0 to request a
default validity period.
input_chan_bindings channel bindings, read, optional
Application-specified bindings. Allows
application to securely bind channel
identification information to the security
context. Specify GSS_C_NO_CHANNEL_BINDINGS
if channel bindings are not used.
input_token buffer, opaque, read, optional (see text)
Token received from peer application.
Supply GSS_C_NO_BUFFER, or a pointer to
a buffer containing the value GSS_C_EMPTY_BUFFER
on initial call.
actual_mech_type OID, modify, optional
Actual mechanism used. The OID returned via
this parameter will be a pointer to static
storage that should be treated as read-only;
In particular the application should not attempt
to free it. Specify NULL if not required.
output_token buffer, opaque, modify
token to be sent to peer application. If
the length field of the returned buffer is
zero, no token need be sent to the peer
application. Storage associated with this
buffer must be freed by the application
after use with a call to gss_release_buffer().
ret_flags bit-mask, modify, optional
Contains various independent flags, each of which
indicates that the context supports a specific
service option. Specify NULL if not
required. Symbolic names are provided
for each flag, and the symbolic names
corresponding to the required flags should be
logically-ANDed with the ret_flags value to test
whether a given option is supported by the
context. The flags are:
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GSS_C_DELEG_FLAG
True - Credentials were delegated to
the remote peer
False - No credentials were delegated
GSS_C_MUTUAL_FLAG
True - The remote peer has authenticated
itself.
False - Remote peer has not authenticated
itself.
GSS_C_REPLAY_FLAG
True - replay of protected messages
will be detected
False - replayed messages will not be
detected
GSS_C_SEQUENCE_FLAG
True - out-of-sequence protected
messages will be detected
False - out-of-sequence messages will
not be detected
GSS_C_CONF_FLAG
True - Confidentiality service may be
invoked by calling gss_wrap routine
False - No confidentiality service (via
gss_wrap) available. gss_wrap will
provide message encapsulation,
data-origin authentication and
integrity services only.
GSS_C_INTEG_FLAG
True - Integrity service may be invoked by
calling either gss_get_mic or gss_wrap
routines.
False - Per-message integrity service
unavailable.
GSS_C_ANON_FLAG
True - The initiator's identity has not been
revealed, and will not be revealed if
any emitted token is passed to the
acceptor.
False - The initiator's identity has been or
will be authenticated normally.
GSS_C_PROT_READY_FLAG
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True - Protection services (as specified
by the states of the GSS_C_CONF_FLAG
and GSS_C_INTEG_FLAG) are available for
use if the accompanying major status
return value is either GSS_S_COMPLETE or
GSS_S_CONTINUE_NEEDED.
False - Protection services (as specified
by the states of the GSS_C_CONF_FLAG
and GSS_C_INTEG_FLAG) are available
only if the accompanying major status
return value is GSS_S_COMPLETE.
GSS_C_TRANS_FLAG
True - The resultant security context may
be transferred to other processes via
a call to gss_export_sec_context().
False - The security context is not
transferable.
All other bits should be set to zero.
time_rec Integer, modify, optional
number of seconds for which the context
will remain valid. If the implementation does
not support context expiration, the value
GSS_C_INDEFINITE will be returned. Specify
NULL if not required.
Function value: GSS status code
GSS_S_COMPLETE Successful completion
GSS_S_CONTINUE_NEEDED Indicates that a token from the peer
application is required to complete the
context, and that gss_init_sec_context
must be called again with that token.
GSS_S_DEFECTIVE_TOKEN Indicates that consistency checks performed
on the input_token failed
GSS_S_DEFECTIVE_CREDENTIAL Indicates that consistency checks
performed on the credential failed.
GSS_S_NO_CRED The supplied credentials were not valid for
context initiation, or the credential handle
did not reference any credentials.
GSS_S_CREDENTIALS_EXPIRED The referenced credentials have expired
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GSS_S_BAD_BINDINGS The input_token contains different channel
bindings to those specified via the
input_chan_bindings parameter
GSS_S_BAD_SIG The input_token contains an invalid MIC, or a MIC
that could not be verified
GSS_S_OLD_TOKEN The input_token was too old. This is a fatal
error during context establishment
GSS_S_DUPLICATE_TOKEN The input_token is valid, but is a duplicate
of a token already processed. This is a
fatal error during context establishment.
GSS_S_NO_CONTEXT Indicates that the supplied context handle did
not refer to a valid context
GSS_S_BAD_NAMETYPE The provided target_name parameter contained an
invalid or unsupported type of name
GSS_S_BAD_NAME The provided target_name parameter was ill-formed.
GSS_S_BAD_MECH The specified mechanism is not supported by the
provided credential, or is unrecognized by the
implementation.
5.20. gss_inquire_context
OM_uint32 gss_inquire_context (
OM_uint32 *minor_status,
const gss_ctx_id_t context_handle,
gss_name_t *src_name,
gss_name_t *targ_name,
OM_uint32 *lifetime_rec,
gss_OID *mech_type,
OM_uint32 *ctx_flags,
int *locally_initiated,
int *open )
Purpose:
Obtains information about a security context. The caller must
already have obtained a handle that refers to the context, although
the context need not be fully established.
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Parameters:
minor_status Integer, modify
Mechanism specific status code
context_handle gss_ctx_id_t, read
A handle that refers to the security context.
src_name gss_name_t, modify, optional
The name of the context initiator.
If the context was established using anonymous
authentication, and if the application invoking
gss_inquire_context is the context acceptor,
an anonymous name will be returned. Storage
associated with this name must be freed by the
application after use with a call to
gss_release_name(). Specify NULL if not
required.
targ_name gss_name_t, modify, optional
The name of the context acceptor.
Storage associated with this name must be
freed by the application after use with a call
to gss_release_name(). If the context acceptor
did not authenticate itself, and if the initiator
did not specify a target name in its call to
gss_init_sec_context(), the value GSS_C_NO_NAME
will be returned. Specify NULL if not required.
lifetime_rec Integer, modify, optional
The number of seconds for which the context
will remain valid. If the context has
expired, this parameter will be set to zero.
If the implementation does not support
context expiration, the value
GSS_C_INDEFINITE will be returned. Specify
NULL if not required.
mech_type gss_OID, modify, optional
The security mechanism providing the
context. The returned OID will be a
pointer to static storage that should
be treated as read-only by the application;
in particular the application should not
attempt to free it. Specify NULL if not
required.
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ctx_flags bit-mask, modify, optional
Contains various independent flags, each of
which indicates that the context supports
(or is expected to support, if ctx_open is
false) a specific service option. If not
needed, specify NULL. Symbolic names are
provided for each flag, and the symbolic names
corresponding to the required flags
should be logically-ANDed with the ret_flags
value to test whether a given option is
supported by the context. The flags are:
GSS_C_DELEG_FLAG
True - Credentials were delegated from
the initiator to the acceptor.
False - No credentials were delegated
GSS_C_MUTUAL_FLAG
True - The acceptor was authenticated
to the initiator
False - The acceptor did not authenticate
itself.
GSS_C_REPLAY_FLAG
True - replay of protected messages
will be detected
False - replayed messages will not be
detected
GSS_C_SEQUENCE_FLAG
True - out-of-sequence protected
messages will be detected
False - out-of-sequence messages will not
be detected
GSS_C_CONF_FLAG
True - Confidentiality service may be invoked
by calling gss_wrap routine
False - No confidentiality service (via
gss_wrap) available. gss_wrap will
provide message encapsulation,
data-origin authentication and
integrity services only.
GSS_C_INTEG_FLAG
True - Integrity service may be invoked by
calling either gss_get_mic or gss_wrap
routines.
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False - Per-message integrity service
unavailable.
GSS_C_ANON_FLAG
True - The initiator's identity will not
be revealed to the acceptor.
The src_name parameter (if
requested) contains an anonymous
internal name.
False - The initiator has been
authenticated normally.
GSS_C_PROT_READY_FLAG
True - Protection services (as specified
by the states of the GSS_C_CONF_FLAG
and GSS_C_INTEG_FLAG) are available
for use.
False - Protection services (as specified
by the states of the GSS_C_CONF_FLAG
and GSS_C_INTEG_FLAG) are available
only if the context is fully
established (i.e. if the open parameter
is non-zero).
GSS_C_TRANS_FLAG
True - The resultant security context may
be transferred to other processes via
a call to gss_export_sec_context().
False - The security context is not
transferable.
locally_initiated Boolean, modify
Non-zero if the invoking application is the
context initiator.
Specify NULL if not required.
open Boolean, modify
Non-zero if the context is fully established;
Zero if a context-establishment token
is expected from the peer application.
Specify NULL if not required.
Function value: GSS status code
GSS_S_COMPLETE Successful completion
GSS_S_NO_CONTEXT The referenced context could not be accessed.
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5.21. gss_inquire_cred
OM_uint32 gss_inquire_cred (
OM_uint32 *minor_status,
const gss_cred_id_t cred_handle,
gss_name_t *name,
OM_uint32 *lifetime,
gss_cred_usage_t *cred_usage,
gss_OID_set *mechanisms )
Purpose:
Obtains information about a credential.
Parameters:
minor_status Integer, modify
Mechanism specific status code
cred_handle gss_cred_id_t, read
A handle that refers to the target credential.
Specify GSS_C_NO_CREDENTIAL to inquire about
the default initiator principal.
name gss_name_t, modify, optional
The name whose identity the credential asserts.
Storage associated with this name should be freed
by the application after use with a call to
gss_release_name(). Specify NULL if not required.
lifetime Integer, modify, optional
The number of seconds for which the credential
will remain valid. If the credential has
expired, this parameter will be set to zero.
If the implementation does not support
credential expiration, the value
GSS_C_INDEFINITE will be returned. Specify
NULL if not required.
cred_usage gss_cred_usage_t, modify, optional
How the credential may be used. One of the
following:
GSS_C_INITIATE
GSS_C_ACCEPT
GSS_C_BOTH
Specify NULL if not required.
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mechanisms gss_OID_set, modify, optional
Set of mechanisms supported by the credential.
Storage associated with this OID set must be
freed by the application after use with a call
to gss_release_oid_set(). Specify NULL if not
required.
Function value: GSS status code
GSS_S_COMPLETE Successful completion
GSS_S_NO_CRED The referenced credentials could not be accessed.
GSS_S_DEFECTIVE_CREDENTIAL The referenced credentials were invalid.
GSS_S_CREDENTIALS_EXPIRED The referenced credentials have expired.
If the lifetime parameter was not passed as NULL,
it will be set to 0.
5.22. gss_inquire_cred_by_mech
OM_uint32 gss_inquire_cred_by_mech (
OM_uint32 *minor_status,
const gss_cred_id_t cred_handle,
const gss_OID mech_type,
gss_name_t *name,
OM_uint32 *initiator_lifetime,
OM_uint32 *acceptor_lifetime,
gss_cred_usage_t *cred_usage )
Purpose:
Obtains per-mechanism information about a credential.
Parameters:
minor_status Integer, modify
Mechanism specific status code
cred_handle gss_cred_id_t, read
A handle that refers to the target credential.
Specify GSS_C_NO_CREDENTIAL to inquire about
the default initiator principal.
mech_type gss_OID, read
The mechanism for which information should be
returned.
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name gss_name_t, modify, optional
The name whose identity the credential asserts.
Storage associated with this name must be
freed by the application after use with a call
to gss_release_name(). Specify NULL if not
required.
initiator_lifetime Integer, modify, optional
The number of seconds for which the credential
will remain capable of initiating security contexts
under the specified mechanism. If the credential
can no longer be used to initiate contexts, or if
the credential usage for this mechanism is
GSS_C_ACCEPT, this parameter will be set to zero.
If the implementation does not support expiration
of initiator credentials, the value
GSS_C_INDEFINITE will be returned. Specify NULL
if not required.
acceptor_lifetime Integer, modify, optional
The number of seconds for which the credential
will remain capable of accepting security contexts
under the specified mechanism. If the credential
can no longer be used to accept contexts, or if
the credential usage for this mechanism is
GSS_C_INITIATE, this parameter will be set to zero.
If the implementation does not support expiration
of acceptor credentials, the value GSS_C_INDEFINITE
will be returned. Specify NULL if not required.
cred_usage gss_cred_usage_t, modify, optional
How the credential may be used with the specified
mechanism. One of the following:
GSS_C_INITIATE
GSS_C_ACCEPT
GSS_C_BOTH
Specify NULL if not required.
Function value: GSS status code
GSS_S_COMPLETE Successful completion
GSS_S_NO_CRED The referenced credentials could not be accessed.
GSS_S_DEFECTIVE_CREDENTIAL The referenced credentials were invalid.
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GSS_S_CREDENTIALS_EXPIRED The referenced credentials have expired.
If the lifetime parameter was not passed as NULL,
it will be set to 0.
5.23. gss_inquire_mechs_for_name
OM_uint32 gss_inquire_mechs_for_name (
OM_uint32 *minor_status,
const gss_name_t input_name,
gss_OID_set *mech_types )
Purpose:
Returns the set of mechanisms supported by the GSS-API implementation
that may be able to process the specified name.
Each mechanism returned will recognize at least one element within
the name. It is permissible for this routine to be implemented
within a mechanism-independent GSS-API layer, using the type
information contained within the presented name, and based on
registration information provided by individual mechanism
implementations. This means that the returned mech_types set may
indicate that a particular mechanism will understand the name when in
fact it would refuse to accept the name as input to
gss_canonicalize_name, gss_init_sec_context, gss_acquire_cred or
gss_add_cred (due to some property of the specific name, as opposed
to the name type). Thus this routine should be used only as a pre-
filter for a call to a subsequent mechanism-specific routine.
Parameters:
minor_status Integer, modify
Implementation specific status code.
input_name gss_name_t, read
The name to which the inquiry relates.
mech_types gss_OID_set, modify
Set of mechanisms that may support the
specified name. The returned OID set
must be freed by the caller after use
with a call to gss_release_oid_set().
Function value: GSS status code
GSS_S_COMPLETE Successful completion
GSS_S_BAD_NAME The input_name parameter was ill-formed.
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GSS_S_BAD_NAMETYPE The input_name parameter contained an invalid or
unsupported type of name
5.24. gss_inquire_names_for_mech
OM_uint32 gss_inquire_names_for_mech (
OM_uint32 *minor_status,
const gss_OID mechanism,
gss_OID_set *name_types)
Purpose:
Returns the set of nametypes supported by the specified mechanism.
Parameters:
minor_status Integer, modify
Implementation specific status code.
mechanism gss_OID, read
The mechanism to be interrogated.
name_types gss_OID_set, modify
Set of name-types supported by the specified
mechanism. The returned OID set must be
freed by the application after use with a
call to gss_release_oid_set().
Function value: GSS status code
GSS_S_COMPLETE Successful completion
5.25. gss_process_context_token
OM_uint32 gss_process_context_token (
OM_uint32 *minor_status,
const gss_ctx_id_t context_handle,
const gss_buffer_t token_buffer)
Purpose:
Provides a way to pass an asynchronous token to the security service.
Most context-level tokens are emitted and processed synchronously by
gss_init_sec_context and gss_accept_sec_context, and the application
is informed as to whether further tokens are expected by the
GSS_C_CONTINUE_NEEDED major status bit. Occasionally, a mechanism
may need to emit a context-level token at a point when the peer
entity is not expecting a token. For example, the initiator's final
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call to gss_init_sec_context may emit a token and return a status of
GSS_S_COMPLETE, but the acceptor's call to gss_accept_sec_context may
fail. The acceptor's mechanism may wish to send a token containing
an error indication to the initiator, but the initiator is not
expecting a token at this point, believing that the context is fully
established. Gss_process_context_token provides a way to pass such a
token to the mechanism at any time.
Parameters:
minor_status Integer, modify
Implementation specific status code.
context_handle gss_ctx_id_t, read
context handle of context on which token is to
be processed
token_buffer buffer, opaque, read
token to process
Function value: GSS status code
GSS_S_COMPLETE Successful completion
GSS_S_DEFECTIVE_TOKEN Indicates that consistency checks performed
on the token failed
GSS_S_NO_CONTEXT The context_handle did not refer to a valid context
5.26. gss_release_buffer
OM_uint32 gss_release_buffer (
OM_uint32 *minor_status,
gss_buffer_t buffer)
Purpose:
Free storage associated with a buffer. The storage must have been
allocated by a GSS-API routine. In addition to freeing the
associated storage, the routine will zero the length field in the
descriptor to which the buffer parameter refers, and implementations
are encouraged to additionally set the pointer field in the
descriptor to NULL. Any buffer object returned by a GSS-API routine
may be passed to gss_release_buffer (even if there is no storage
associated with the buffer).
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Parameters:
minor_status Integer, modify
Mechanism specific status code
buffer buffer, modify
The storage associated with the buffer will be
deleted. The gss_buffer_desc object will not
be freed, but its length field will be zeroed.
Function value: GSS status code
GSS_S_COMPLETE Successful completion
5.27. gss_release_cred
OM_uint32 gss_release_cred (
OM_uint32 *minor_status,
gss_cred_id_t *cred_handle)
Purpose:
Informs GSS-API that the specified credential handle is no longer
required by the application, and frees associated resources.
Implementations are encouraged to set the cred_handle to
GSS_C_NO_CREDENTIAL on successful completion of this call.
Parameters:
cred_handle gss_cred_id_t, modify, optional
Opaque handle identifying credential
to be released. If GSS_C_NO_CREDENTIAL
is supplied, the routine will complete
successfully, but will do nothing.
minor_status Integer, modify
Mechanism specific status code.
Function value: GSS status code
GSS_S_COMPLETE Successful completion
GSS_S_NO_CRED Credentials could not be accessed.
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5.28. gss_release_name
OM_uint32 gss_release_name (
OM_uint32 *minor_status,
gss_name_t *name)
Purpose:
Free GSSAPI-allocated storage associated with an internal-form name.
Implementations are encouraged to set the name to GSS_C_NO_NAME on
successful completion of this call.
Parameters:
minor_status Integer, modify
Mechanism specific status code
name gss_name_t, modify
The name to be deleted
Function value: GSS status code
GSS_S_COMPLETE Successful completion
GSS_S_BAD_NAME The name parameter did not contain a valid name
5.29. gss_release_oid_set
OM_uint32 gss_release_oid_set (
OM_uint32 *minor_status,
gss_OID_set *set)
Purpose:
Free storage associated with a GSSAPI-generated gss_OID_set object.
The set parameter must refer to an OID-set that was returned from a
GSS-API routine. gss_release_oid_set() will free the storage
associated with each individual member OID, the OID set's elements
array, and the gss_OID_set_desc.
Implementations are encouraged to set the gss_OID_set parameter to
GSS_C_NO_OID_SET on successful completion of this routine.
Parameters:
minor_status Integer, modify
Mechanism specific status code
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set Set of Object IDs, modify
The storage associated with the gss_OID_set
will be deleted.
Function value: GSS status code
GSS_S_COMPLETE Successful completion
5.30. gss_test_oid_set_member
OM_uint32 gss_test_oid_set_member (
OM_uint32 *minor_status,
const gss_OID member,
const gss_OID_set set,
int *present)
Purpose:
Interrogate an Object Identifier set to determine whether a specified
Object Identifier is a member. This routine is intended to be used
with OID sets returned by gss_indicate_mechs(), gss_acquire_cred(),
and gss_inquire_cred(), but will also work with user-generated sets.
Parameters:
minor_status Integer, modify
Mechanism specific status code
member Object ID, read
The object identifier whose presence
is to be tested.
set Set of Object ID, read
The Object Identifier set.
present Boolean, modify
non-zero if the specified OID is a member
of the set, zero if not.
Function value: GSS status code
GSS_S_COMPLETE Successful completion
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5.31. gss_unwrap
OM_uint32 gss_unwrap (
OM_uint32 *minor_status,
const gss_ctx_id_t context_handle,
const gss_buffer_t input_message_buffer,
gss_buffer_t output_message_buffer,
int *conf_state,
gss_qop_t *qop_state)
Purpose:
Converts a message previously protected by gss_wrap back to a usable
form, verifying the embedded MIC. The conf_state parameter indicates
whether the message was encrypted; the qop_state parameter indicates
the strength of protection that was used to provide the
confidentiality and integrity services.
Since some application-level protocols may wish to use tokens emitted
by gss_wrap() to provide "secure framing", implementations must
support the wrapping and unwrapping of zero-length messages.
Parameters:
minor_status Integer, modify
Mechanism specific status code.
context_handle gss_ctx_id_t, read
Identifies the context on which the message
arrived
input_message_buffer buffer, opaque, read
protected message
output_message_buffer buffer, opaque, modify
Buffer to receive unwrapped message.
Storage associated with this buffer must
be freed by the application after use use
with a call to gss_release_buffer().
conf_state boolean, modify, optional
Non-zero - Confidentiality and integrity
protection were used
Zero - Integrity service only was used
Specify NULL if not required
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qop_state gss_qop_t, modify, optional
Quality of protection provided.
Specify NULL if not required
Function value: GSS status code
GSS_S_COMPLETE Successful completion
GSS_S_DEFECTIVE_TOKEN The token failed consistency checks
GSS_S_BAD_SIG The MIC was incorrect
GSS_S_DUPLICATE_TOKEN The token was valid, and contained a correct
MIC for the message, but it had already been
processed
GSS_S_OLD_TOKEN The token was valid, and contained a correct MIC
for the message, but it is too old to check for
duplication.
GSS_S_UNSEQ_TOKEN The token was valid, and contained a correct MIC
for the message, but has been verified out of
sequence; a later token has already been
received.
GSS_S_GAP_TOKEN The token was valid, and contained a correct MIC
for the message, but has been verified out of
sequence; an earlier expected token has not yet
been received.
GSS_S_CONTEXT_EXPIRED The context has already expired
GSS_S_NO_CONTEXT The context_handle parameter did not identify
a valid context
5.32. gss_verify_mic
OM_uint32 gss_verify_mic (
OM_uint32 *minor_status,
const gss_ctx_id_t context_handle,
const gss_buffer_t message_buffer,
const gss_buffer_t token_buffer,
gss_qop_t *qop_state)
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Purpose:
Verifies that a cryptographic MIC, contained in the token parameter,
fits the supplied message. The qop_state parameter allows a message
recipient to determine the strength of protection that was applied to
the message.
Since some application-level protocols may wish to use tokens emitted
by gss_wrap() to provide "secure framing", implementations must
support the calculation and verification of MICs over zero-length
messages.
Parameters:
minor_status Integer, modify
Mechanism specific status code.
context_handle gss_ctx_id_t, read
Identifies the context on which the message
arrived
message_buffer buffer, opaque, read
Message to be verified
token_buffer buffer, opaque, read
Token associated with message
qop_state gss_qop_t, modify, optional
quality of protection gained from MIC
Specify NULL if not required
Function value: GSS status code
GSS_S_COMPLETE Successful completion
GSS_S_DEFECTIVE_TOKEN The token failed consistency checks
GSS_S_BAD_SIG The MIC was incorrect
GSS_S_DUPLICATE_TOKEN The token was valid, and contained a correct
MIC for the message, but it had already been
processed
GSS_S_OLD_TOKEN The token was valid, and contained a correct MIC
for the message, but it is too old to check for
duplication.
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GSS_S_UNSEQ_TOKEN The token was valid, and contained a correct MIC
for the message, but has been verified out of
sequence; a later token has already been received.
GSS_S_GAP_TOKEN The token was valid, and contained a correct MIC
for the message, but has been verified out of
sequence; an earlier expected token has not yet
been received.
GSS_S_CONTEXT_EXPIRED The context has already expired
GSS_S_NO_CONTEXT The context_handle parameter did not identify a
valid context
5.33. gss_wrap
OM_uint32 gss_wrap (
OM_uint32 *minor_status,
const gss_ctx_id_t context_handle,
int conf_req_flag,
gss_qop_t qop_req
const gss_buffer_t input_message_buffer,
int *conf_state,
gss_buffer_t output_message_buffer )
Purpose:
Attaches a cryptographic MIC and optionally encrypts the specified
input_message. The output_message contains both the MIC and the
message. The qop_req parameter allows a choice between several
cryptographic algorithms, if supported by the chosen mechanism.
Since some application-level protocols may wish to use tokens emitted
by gss_wrap() to provide "secure framing", implementations must
support the wrapping of zero-length messages.
Parameters:
minor_status Integer, modify
Mechanism specific status code.
context_handle gss_ctx_id_t, read
Identifies the context on which the message
will be sent
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conf_req_flag boolean, read
Non-zero - Both confidentiality and integrity
services are requested
Zero - Only integrity service is requested
qop_req gss_qop_t, read, optional
Specifies required quality of protection. A
mechanism-specific default may be requested by
setting qop_req to GSS_C_QOP_DEFAULT. If an
unsupported protection strength is requested,
gss_wrap will return a major_status of
GSS_S_BAD_QOP.
input_message_buffer buffer, opaque, read
Message to be protected
conf_state boolean, modify, optional
Non-zero - Confidentiality, data origin
authentication and integrity
services have been applied
Zero - Integrity and data origin services only
has been applied.
Specify NULL if not required
output_message_buffer buffer, opaque, modify
Buffer to receive protected message.
Storage associated with this message must
be freed by the application after use with
a call to gss_release_buffer().
Function value: GSS status code
GSS_S_COMPLETE Successful completion
GSS_S_CONTEXT_EXPIRED The context has already expired
GSS_S_NO_CONTEXT The context_handle parameter did not identify a
valid context
GSS_S_BAD_QOP The specified QOP is not supported by the
mechanism.
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5.34. gss_wrap_size_limit
OM_uint32 gss_wrap_size_limit (
OM_uint32 *minor_status,
const gss_ctx_id_t context_handle,
int conf_req_flag,
gss_qop_t qop_req,
OM_uint32 req_output_size,
OM_uint32 *max_input_size)
Purpose:
Allows an application to determine the maximum message size that, if
presented to gss_wrap with the same conf_req_flag and qop_req
parameters, will result in an output token containing no more than
req_output_size bytes.
This call is intended for use by applications that communicate over
protocols that impose a maximum message size. It enables the
application to fragment messages prior to applying protection.
GSS-API implementations are recommended but not required to detect
invalid QOP values when gss_wrap_size_limit() is called. This routine
guarantees only a maximum message size, not the availability of
specific QOP values for message protection.
Successful completion of this call does not guarantee that gss_wrap
will be able to protect a message of length max_input_size bytes,
since this ability may depend on the availability of system resources
at the time that gss_wrap is called. However, if the implementation
itself imposes an upper limit on the length of messages that may be
processed by gss_wrap, the implementation should not return a value
via max_input_bytes that is greater than this length.
Parameters:
minor_status Integer, modify
Mechanism specific status code
context_handle gss_ctx_id_t, read
A handle that refers to the security over
which the messages will be sent.
conf_req_flag Boolean, read
Indicates whether gss_wrap will be asked
to apply confidentiality protection in
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addition to integrity protection. See
the routine description for gss_wrap
for more details.
qop_req gss_qop_t, read
Indicates the level of protection that
gss_wrap will be asked to provide. See
the routine description for gss_wrap for
more details.
req_output_size Integer, read
The desired maximum size for tokens emitted
by gss_wrap.
max_input_size Integer, modify
The maximum input message size that may
be presented to gss_wrap in order to
guarantee that the emitted token shall
be no larger than req_output_size bytes.
Function value: GSS status code
GSS_S_COMPLETE Successful completion
GSS_S_NO_CONTEXT The referenced context could not be accessed.
GSS_S_CONTEXT_EXPIRED The context has expired.
GSS_S_BAD_QOP The specified QOP is not supported by the
mechanism.
6. Security Considerations
This document specifies a service interface for security facilities
and services; as such, security considerations appear throughout the
specification. Nonetheless, it is appropriate to summarize certain
specific points relevant to GSS-API implementors and calling
applications. Usage of the GSS-API interface does not in itself
provide security services or assurance; instead, these attributes are
dependent on the underlying mechanism(s) which support a GSS-API
implementation. Callers must be attentive to the requests made to
GSS-API calls and to the status indicators returned by GSS-API, as
these specify the security service characteristics which GSS-API will
provide. When the interprocess context transfer facility is used,
appropriate local controls should be applied to constrain access to
interprocess tokens and to the sensitive data which they contain.
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Appendix A. GSS-API C header file gssapi.h
C-language GSS-API implementations should include a copy of the
following header-file.
#ifndef GSSAPI_H_
#define GSSAPI_H_
/*
* First, include stddef.h to get size_t defined.
*/
#include
/*
* If the platform supports the xom.h header file, it should be
* included here.
*/
#include
/*
* Now define the three implementation-dependent types.
*/
typedef gss_ctx_id_t;
typedef gss_cred_id_t;
typedef gss_name_t;
/*
* The following type must be defined as the smallest natural
* unsigned integer supported by the platform that has at least
* 32 bits of precision.
*/
typedef gss_uint32;
#ifdef OM_STRING
/*
* We have included the xom.h header file. Verify that OM_uint32
* is defined correctly.
*/
#if sizeof(gss_uint32) != sizeof(OM_uint32)
#error Incompatible definition of OM_uint32 from xom.h
#endif
typedef OM_object_identifier gss_OID_desc, *gss_OID;
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#else
/*
* We can't use X/Open definitions, so roll our own.
*/
typedef gss_uint32 OM_uint32;
typedef struct gss_OID_desc_struct {
OM_uint32 length;
void *elements;
} gss_OID_desc, *gss_OID;
#endif
typedef struct gss_OID_set_desc_struct {
size_t count;
gss_OID elements;
} gss_OID_set_desc, *gss_OID_set;
typedef struct gss_buffer_desc_struct {
size_t length;
void *value;
} gss_buffer_desc, *gss_buffer_t;
typedef struct gss_channel_bindings_struct {
OM_uint32 initiator_addrtype;
gss_buffer_desc initiator_address;
OM_uint32 acceptor_addrtype;
gss_buffer_desc acceptor_address;
gss_buffer_desc application_data;
} *gss_channel_bindings_t;
/*
* For now, define a QOP-type as an OM_uint32
*/
typedef OM_uint32 gss_qop_t;
typedef int gss_cred_usage_t;
/*
* Flag bits for context-level services.
*/
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RFC 2744 GSS-API V2: C-bindings January 2000
#define GSS_C_DELEG_FLAG 1
#define GSS_C_MUTUAL_FLAG 2
#define GSS_C_REPLAY_FLAG 4
#define GSS_C_SEQUENCE_FLAG 8
#define GSS_C_CONF_FLAG 16
#define GSS_C_INTEG_FLAG 32
#define GSS_C_ANON_FLAG 64
#define GSS_C_PROT_READY_FLAG 128
#define GSS_C_TRANS_FLAG 256
/*
* Credential usage options
*/
#define GSS_C_BOTH 0
#define GSS_C_INITIATE 1
#define GSS_C_ACCEPT 2
/*
* Status code types for gss_display_status
*/
#define GSS_C_GSS_CODE 1
#define GSS_C_MECH_CODE 2
/*
* The constant definitions for channel-bindings address families
*/
#define GSS_C_AF_UNSPEC 0
#define GSS_C_AF_LOCAL 1
#define GSS_C_AF_INET 2
#define GSS_C_AF_IMPLINK 3
#define GSS_C_AF_PUP 4
#define GSS_C_AF_CHAOS 5
#define GSS_C_AF_NS 6
#define GSS_C_AF_NBS 7
#define GSS_C_AF_ECMA 8
#define GSS_C_AF_DATAKIT 9
#define GSS_C_AF_CCITT 10
#define GSS_C_AF_SNA 11
#define GSS_C_AF_DECnet 12
#define GSS_C_AF_DLI 13
#define GSS_C_AF_LAT 14
#define GSS_C_AF_HYLINK 15
#define GSS_C_AF_APPLETALK 16
#define GSS_C_AF_BSC 17
#define GSS_C_AF_DSS 18
#define GSS_C_AF_OSI 19
#define GSS_C_AF_X25 21
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RFC 2744 GSS-API V2: C-bindings January 2000
#define GSS_C_AF_NULLADDR 255
/*
* Various Null values
*/
#define GSS_C_NO_NAME ((gss_name_t) 0)
#define GSS_C_NO_BUFFER ((gss_buffer_t) 0)
#define GSS_C_NO_OID ((gss_OID) 0)
#define GSS_C_NO_OID_SET ((gss_OID_set) 0)
#define GSS_C_NO_CONTEXT ((gss_ctx_id_t) 0)
#define GSS_C_NO_CREDENTIAL ((gss_cred_id_t) 0)
#define GSS_C_NO_CHANNEL_BINDINGS ((gss_channel_bindings_t) 0)
#define GSS_C_EMPTY_BUFFER {0, NULL}
/*
* Some alternate names for a couple of the above
* values. These are defined for V1 compatibility.
*/
#define GSS_C_NULL_OID GSS_C_NO_OID
#define GSS_C_NULL_OID_SET GSS_C_NO_OID_SET
/*
* Define the default Quality of Protection for per-message
* services. Note that an implementation that offers multiple
* levels of QOP may define GSS_C_QOP_DEFAULT to be either zero
* (as done here) to mean "default protection", or to a specific
* explicit QOP value. However, a value of 0 should always be
* interpreted by a GSS-API implementation as a request for the
* default protection level.
*/
#define GSS_C_QOP_DEFAULT 0
/*
* Expiration time of 2^32-1 seconds means infinite lifetime for a
* credential or security context
*/
#define GSS_C_INDEFINITE 0xfffffffful
/*
* The implementation must reserve static storage for a
* gss_OID_desc object containing the value
* {10, (void *)"\x2a\x86\x48\x86\xf7\x12"
* "\x01\x02\x01\x01"},
* corresponding to an object-identifier value of
* {iso(1) member-body(2) United States(840) mit(113554)
* infosys(1) gssapi(2) generic(1) user_name(1)}. The constant
* GSS_C_NT_USER_NAME should be initialized to point
* to that gss_OID_desc.
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RFC 2744 GSS-API V2: C-bindings January 2000
*/
extern gss_OID GSS_C_NT_USER_NAME;
/*
* The implementation must reserve static storage for a
* gss_OID_desc object containing the value
* {10, (void *)"\x2a\x86\x48\x86\xf7\x12"
* "\x01\x02\x01\x02"},
* corresponding to an object-identifier value of
* {iso(1) member-body(2) United States(840) mit(113554)
* infosys(1) gssapi(2) generic(1) machine_uid_name(2)}.
* The constant GSS_C_NT_MACHINE_UID_NAME should be
* initialized to point to that gss_OID_desc.
*/
extern gss_OID GSS_C_NT_MACHINE_UID_NAME;
/*
* The implementation must reserve static storage for a
* gss_OID_desc object containing the value
* {10, (void *)"\x2a\x86\x48\x86\xf7\x12"
* "\x01\x02\x01\x03"},
* corresponding to an object-identifier value of
* {iso(1) member-body(2) United States(840) mit(113554)
* infosys(1) gssapi(2) generic(1) string_uid_name(3)}.
* The constant GSS_C_NT_STRING_UID_NAME should be
* initialized to point to that gss_OID_desc.
*/
extern gss_OID GSS_C_NT_STRING_UID_NAME;
/*
* The implementation must reserve static storage for a
* gss_OID_desc object containing the value
* {6, (void *)"\x2b\x06\x01\x05\x06\x02"},
* corresponding to an object-identifier value of
* {iso(1) org(3) dod(6) internet(1) security(5)
* nametypes(6) gss-host-based-services(2)). The constant
* GSS_C_NT_HOSTBASED_SERVICE_X should be initialized to point
* to that gss_OID_desc. This is a deprecated OID value, and
* implementations wishing to support hostbased-service names
* should instead use the GSS_C_NT_HOSTBASED_SERVICE OID,
* defined below, to identify such names;
* GSS_C_NT_HOSTBASED_SERVICE_X should be accepted a synonym
* for GSS_C_NT_HOSTBASED_SERVICE when presented as an input
* parameter, but should not be emitted by GSS-API
* implementations
*/
extern gss_OID GSS_C_NT_HOSTBASED_SERVICE_X;
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RFC 2744 GSS-API V2: C-bindings January 2000
/*
* The implementation must reserve static storage for a
* gss_OID_desc object containing the value
* {10, (void *)"\x2a\x86\x48\x86\xf7\x12"
* "\x01\x02\x01\x04"}, corresponding to an
* object-identifier value of {iso(1) member-body(2)
* Unites States(840) mit(113554) infosys(1) gssapi(2)
* generic(1) service_name(4)}. The constant
* GSS_C_NT_HOSTBASED_SERVICE should be initialized
* to point to that gss_OID_desc.
*/
extern gss_OID GSS_C_NT_HOSTBASED_SERVICE;
/*
* The implementation must reserve static storage for a
* gss_OID_desc object containing the value
* {6, (void *)"\x2b\x06\01\x05\x06\x03"},
* corresponding to an object identifier value of
* {1(iso), 3(org), 6(dod), 1(internet), 5(security),
* 6(nametypes), 3(gss-anonymous-name)}. The constant
* and GSS_C_NT_ANONYMOUS should be initialized to point
* to that gss_OID_desc.
*/
extern gss_OID GSS_C_NT_ANONYMOUS;
/*
* The implementation must reserve static storage for a
* gss_OID_desc object containing the value
* {6, (void *)"\x2b\x06\x01\x05\x06\x04"},
* corresponding to an object-identifier value of
* {1(iso), 3(org), 6(dod), 1(internet), 5(security),
* 6(nametypes), 4(gss-api-exported-name)}. The constant
* GSS_C_NT_EXPORT_NAME should be initialized to point
* to that gss_OID_desc.
*/
extern gss_OID GSS_C_NT_EXPORT_NAME;
/* Major status codes */
#define GSS_S_COMPLETE 0
/*
* Some "helper" definitions to make the status code macros obvious.
*/
#define GSS_C_CALLING_ERROR_OFFSET 24
#define GSS_C_ROUTINE_ERROR_OFFSET 16
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RFC 2744 GSS-API V2: C-bindings January 2000
#define GSS_C_SUPPLEMENTARY_OFFSET 0
#define GSS_C_CALLING_ERROR_MASK 0377ul
#define GSS_C_ROUTINE_ERROR_MASK 0377ul
#define GSS_C_SUPPLEMENTARY_MASK 0177777ul
/*
* The macros that test status codes for error conditions.
* Note that the GSS_ERROR() macro has changed slightly from
* the V1 GSS-API so that it now evaluates its argument
* only once.
*/
#define GSS_CALLING_ERROR(x) \
(x & (GSS_C_CALLING_ERROR_MASK << GSS_C_CALLING_ERROR_OFFSET))
#define GSS_ROUTINE_ERROR(x) \
(x & (GSS_C_ROUTINE_ERROR_MASK << GSS_C_ROUTINE_ERROR_OFFSET))
#define GSS_SUPPLEMENTARY_INFO(x) \
(x & (GSS_C_SUPPLEMENTARY_MASK << GSS_C_SUPPLEMENTARY_OFFSET))
#define GSS_ERROR(x) \
(x & ((GSS_C_CALLING_ERROR_MASK << GSS_C_CALLING_ERROR_OFFSET) | \
(GSS_C_ROUTINE_ERROR_MASK << GSS_C_ROUTINE_ERROR_OFFSET)))
/*
* Now the actual status code definitions
*/
/*
* Calling errors:
*/
#define GSS_S_CALL_INACCESSIBLE_READ \
(1ul << GSS_C_CALLING_ERROR_OFFSET)
#define GSS_S_CALL_INACCESSIBLE_WRITE \
(2ul << GSS_C_CALLING_ERROR_OFFSET)
#define GSS_S_CALL_BAD_STRUCTURE \
(3ul << GSS_C_CALLING_ERROR_OFFSET)
/*
* Routine errors:
*/
#define GSS_S_BAD_MECH (1ul <<
GSS_C_ROUTINE_ERROR_OFFSET)
#define GSS_S_BAD_NAME (2ul <<
GSS_C_ROUTINE_ERROR_OFFSET)
#define GSS_S_BAD_NAMETYPE (3ul <<
GSS_C_ROUTINE_ERROR_OFFSET)
#define GSS_S_BAD_BINDINGS (4ul <<
GSS_C_ROUTINE_ERROR_OFFSET)
#define GSS_S_BAD_STATUS (5ul <<
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RFC 2744 GSS-API V2: C-bindings January 2000
GSS_C_ROUTINE_ERROR_OFFSET)
#define GSS_S_BAD_SIG (6ul <<
GSS_C_ROUTINE_ERROR_OFFSET)
#define GSS_S_BAD_MIC GSS_S_BAD_SIG
#define GSS_S_NO_CRED (7ul <<
GSS_C_ROUTINE_ERROR_OFFSET)
#define GSS_S_NO_CONTEXT (8ul <<
GSS_C_ROUTINE_ERROR_OFFSET)
#define GSS_S_DEFECTIVE_TOKEN (9ul <<
GSS_C_ROUTINE_ERROR_OFFSET)
#define GSS_S_DEFECTIVE_CREDENTIAL (10ul <<
GSS_C_ROUTINE_ERROR_OFFSET)
#define GSS_S_CREDENTIALS_EXPIRED (11ul <<
GSS_C_ROUTINE_ERROR_OFFSET)
#define GSS_S_CONTEXT_EXPIRED (12ul <<
GSS_C_ROUTINE_ERROR_OFFSET)
#define GSS_S_FAILURE (13ul <<
GSS_C_ROUTINE_ERROR_OFFSET)
#define GSS_S_BAD_QOP (14ul <<
GSS_C_ROUTINE_ERROR_OFFSET)
#define GSS_S_UNAUTHORIZED (15ul <<
GSS_C_ROUTINE_ERROR_OFFSET)
#define GSS_S_UNAVAILABLE (16ul <<
GSS_C_ROUTINE_ERROR_OFFSET)
#define GSS_S_DUPLICATE_ELEMENT (17ul <<
GSS_C_ROUTINE_ERROR_OFFSET)
#define GSS_S_NAME_NOT_MN (18ul <<
GSS_C_ROUTINE_ERROR_OFFSET)
/*
* Supplementary info bits:
*/
#define GSS_S_CONTINUE_NEEDED \
(1ul << (GSS_C_SUPPLEMENTARY_OFFSET + 0))
#define GSS_S_DUPLICATE_TOKEN \
(1ul << (GSS_C_SUPPLEMENTARY_OFFSET + 1))
#define GSS_S_OLD_TOKEN \
(1ul << (GSS_C_SUPPLEMENTARY_OFFSET + 2))
#define GSS_S_UNSEQ_TOKEN \
(1ul << (GSS_C_SUPPLEMENTARY_OFFSET + 3))
#define GSS_S_GAP_TOKEN \
(1ul << (GSS_C_SUPPLEMENTARY_OFFSET + 4))
/*
* Finally, function prototypes for the GSS-API routines.
*/
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RFC 2744 GSS-API V2: C-bindings January 2000
OM_uint32 gss_acquire_cred
(OM_uint32 , /* minor_status */
const gss_name_t, /* desired_name */
OM_uint32, /* time_req */
const gss_OID_set, /* desired_mechs */
gss_cred_usage_t, /* cred_usage */
gss_cred_id_t , /* output_cred_handle */
gss_OID_set , /* actual_mechs */
OM_uint32 * /* time_rec */
);
OM_uint32 gss_release_cred
(OM_uint32 , /* minor_status */
gss_cred_id_t * /* cred_handle */
);
OM_uint32 gss_init_sec_context
(OM_uint32 , /* minor_status */
const gss_cred_id_t, /* initiator_cred_handle */
gss_ctx_id_t , /* context_handle */
const gss_name_t, /* target_name */
const gss_OID, /* mech_type */
OM_uint32, /* req_flags */
OM_uint32, /* time_req */
const gss_channel_bindings_t,
/* input_chan_bindings */
const gss_buffer_t, /* input_token */
gss_OID , /* actual_mech_type */
gss_buffer_t, /* output_token */
OM_uint32 , /* ret_flags */
OM_uint32 * /* time_rec */
);
OM_uint32 gss_accept_sec_context
(OM_uint32 , /* minor_status */
gss_ctx_id_t , /* context_handle */
const gss_cred_id_t, /* acceptor_cred_handle */
const gss_buffer_t, /* input_token_buffer */
const gss_channel_bindings_t,
/* input_chan_bindings */
gss_name_t , /* src_name */
gss_OID , /* mech_type */
gss_buffer_t, /* output_token */
OM_uint32 , /* ret_flags */
OM_uint32 , /* time_rec */
gss_cred_id_t * /* delegated_cred_handle */
);
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RFC 2744 GSS-API V2: C-bindings January 2000
OM_uint32 gss_process_context_token
(OM_uint32 , /* minor_status */
const gss_ctx_id_t, /* context_handle */
const gss_buffer_t /* token_buffer */
);
OM_uint32 gss_delete_sec_context
(OM_uint32 , /* minor_status */
gss_ctx_id_t , /* context_handle */
gss_buffer_t /* output_token */
);
OM_uint32 gss_context_time
(OM_uint32 , /* minor_status */
const gss_ctx_id_t, /* context_handle */
OM_uint32 * /* time_rec */
);
OM_uint32 gss_get_mic
(OM_uint32 , /* minor_status */
const gss_ctx_id_t, /* context_handle */
gss_qop_t, /* qop_req */
const gss_buffer_t, /* message_buffer */
gss_buffer_t /* message_token */
);
OM_uint32 gss_verify_mic
(OM_uint32 , /* minor_status */
const gss_ctx_id_t, /* context_handle */
const gss_buffer_t, /* message_buffer */
const gss_buffer_t, /* token_buffer */
gss_qop_t * /* qop_state */
);
OM_uint32 gss_wrap
(OM_uint32 , /* minor_status */
const gss_ctx_id_t, /* context_handle */
int, /* conf_req_flag */
gss_qop_t, /* qop_req */
const gss_buffer_t, /* input_message_buffer */
int , /* conf_state */
gss_buffer_t /* output_message_buffer */
);
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RFC 2744 GSS-API V2: C-bindings January 2000
OM_uint32 gss_unwrap
(OM_uint32 , /* minor_status */
const gss_ctx_id_t, /* context_handle */
const gss_buffer_t, /* input_message_buffer */
gss_buffer_t, /* output_message_buffer */
int , /* conf_state */
gss_qop_t * /* qop_state */
);
OM_uint32 gss_display_status
(OM_uint32 , /* minor_status */
OM_uint32, /* status_value */
int, /* status_type */
const gss_OID, /* mech_type */
OM_uint32 , /* message_context */
gss_buffer_t /* status_string */
);
OM_uint32 gss_indicate_mechs
(OM_uint32 , /* minor_status */
gss_OID_set * /* mech_set */
);
OM_uint32 gss_compare_name
(OM_uint32 , /* minor_status */
const gss_name_t, /* name1 */
const gss_name_t, /* name2 */
int * /* name_equal */
);
OM_uint32 gss_display_name
(OM_uint32 , /* minor_status */
const gss_name_t, /* input_name */
gss_buffer_t, /* output_name_buffer */
gss_OID * /* output_name_type */
);
OM_uint32 gss_import_name
(OM_uint32 , /* minor_status */
const gss_buffer_t, /* input_name_buffer */
const gss_OID, /* input_name_type */
gss_name_t * /* output_name */
);
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RFC 2744 GSS-API V2: C-bindings January 2000
OM_uint32 gss_export_name
(OM_uint32, /* minor_status */
const gss_name_t, /* input_name */
gss_buffer_t /* exported_name */
);
OM_uint32 gss_release_name
(OM_uint32 *, /* minor_status */
gss_name_t * /* input_name */
);
OM_uint32 gss_release_buffer
(OM_uint32 , /* minor_status */
gss_buffer_t /* buffer */
);
OM_uint32 gss_release_oid_set
(OM_uint32 , /* minor_status */
gss_OID_set * /* set */
);
OM_uint32 gss_inquire_cred
(OM_uint32 , /* minor_status */
const gss_cred_id_t, /* cred_handle */
gss_name_t , /* name */
OM_uint32 , /* lifetime */
gss_cred_usage_t , /* cred_usage */
gss_OID_set * /* mechanisms */
);
OM_uint32 gss_inquire_context (
OM_uint32 , /* minor_status */
const gss_ctx_id_t, /* context_handle */
gss_name_t , /* src_name */
gss_name_t , /* targ_name */
OM_uint32 , /* lifetime_rec */
gss_OID , /* mech_type */
OM_uint32 , /* ctx_flags */
int , /* locally_initiated */
int * /* open */
);
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RFC 2744 GSS-API V2: C-bindings January 2000
OM_uint32 gss_wrap_size_limit (
OM_uint32 , /* minor_status */
const gss_ctx_id_t, /* context_handle */
int, /* conf_req_flag */
gss_qop_t, /* qop_req */
OM_uint32, /* req_output_size */
OM_uint32 * /* max_input_size */
);
OM_uint32 gss_add_cred (
OM_uint32 , /* minor_status */
const gss_cred_id_t, /* input_cred_handle */
const gss_name_t, /* desired_name */
const gss_OID, /* desired_mech */
gss_cred_usage_t, /* cred_usage */
OM_uint32, /* initiator_time_req */
OM_uint32, /* acceptor_time_req */
gss_cred_id_t , /* output_cred_handle */
gss_OID_set , /* actual_mechs */
OM_uint32 , /* initiator_time_rec */
OM_uint32 * /* acceptor_time_rec */
);
OM_uint32 gss_inquire_cred_by_mech (
OM_uint32 , /* minor_status */
const gss_cred_id_t, /* cred_handle */
const gss_OID, /* mech_type */
gss_name_t , /* name */
OM_uint32 , /* initiator_lifetime */
OM_uint32 , /* acceptor_lifetime */
gss_cred_usage_t * /* cred_usage */
);
OM_uint32 gss_export_sec_context (
OM_uint32 , /* minor_status */
gss_ctx_id_t , /* context_handle */
gss_buffer_t /* interprocess_token */
);
OM_uint32 gss_import_sec_context (
OM_uint32 , /* minor_status */
const gss_buffer_t, /* interprocess_token */
gss_ctx_id_t * /* context_handle */
);
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RFC 2744 GSS-API V2: C-bindings January 2000
OM_uint32 gss_create_empty_oid_set (
OM_uint32 , /* minor_status */
gss_OID_set * /* oid_set */
);
OM_uint32 gss_add_oid_set_member (
OM_uint32 , /* minor_status */
const gss_OID, /* member_oid */
gss_OID_set * /* oid_set */
);
OM_uint32 gss_test_oid_set_member (
OM_uint32 , /* minor_status */
const gss_OID, /* member */
const gss_OID_set, /* set */
int * /* present */
);
OM_uint32 gss_inquire_names_for_mech (
OM_uint32 , /* minor_status */
const gss_OID, /* mechanism */
gss_OID_set * /* name_types */
);
OM_uint32 gss_inquire_mechs_for_name (
OM_uint32 , /* minor_status */
const gss_name_t, /* input_name */
gss_OID_set * /* mech_types */
);
OM_uint32 gss_canonicalize_name (
OM_uint32 , /* minor_status */
const gss_name_t, /* input_name */
const gss_OID, /* mech_type */
gss_name_t * /* output_name */
);
OM_uint32 gss_duplicate_name (
OM_uint32 , /* minor_status */
const gss_name_t, /* src_name */
gss_name_t * /* dest_name */
);
/*
* The following routines are obsolete variants of gss_get_mic,
* gss_verify_mic, gss_wrap and gss_unwrap. They should be
* provided by GSS-API V2 implementations for backwards
* compatibility with V1 applications. Distinct entrypoints
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RFC 2744 GSS-API V2: C-bindings January 2000
* (as opposed to #defines) should be provided, both to allow
* GSS-API V1 applications to link against GSS-API V2
implementations,
* and to retain the slight parameter type differences between the
* obsolete versions of these routines and their current forms.
*/
OM_uint32 gss_sign
(OM_uint32 , /* minor_status */
gss_ctx_id_t, /* context_handle */
int, /* qop_req */
gss_buffer_t, /* message_buffer */
gss_buffer_t /* message_token */
);
OM_uint32 gss_verify
(OM_uint32 , /* minor_status */
gss_ctx_id_t, /* context_handle */
gss_buffer_t, /* message_buffer */
gss_buffer_t, /* token_buffer */
int * /* qop_state */
);
OM_uint32 gss_seal
(OM_uint32 , /* minor_status */
gss_ctx_id_t, /* context_handle */
int, /* conf_req_flag */
int, /* qop_req */
gss_buffer_t, /* input_message_buffer */
int , /* conf_state */
gss_buffer_t /* output_message_buffer */
);
OM_uint32 gss_unseal
(OM_uint32 , /* minor_status */
gss_ctx_id_t, /* context_handle */
gss_buffer_t, /* input_message_buffer */
gss_buffer_t, /* output_message_buffer */
int , /* conf_state */
int * /* qop_state */
);
#endif /* GSSAPI_H_ */
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Appendix B. Additional constraints for application binary portability
The purpose of this C-bindings document is to encourage source-level
portability of applications across GSS-API implementations on
different platforms and atop different mechanisms. Additional goals
that have not been explicitly addressed by this document are link-
time and run-time portability.
Link-time portability provides the ability to compile an application
against one implementation of GSS-API, and then link it against a
different implementation on the same platform. It is a stricter
requirement than source-level portability.
Run-time portability differs from link-time portability only on those
platforms that implement dynamically loadable GSS-API
implementations, but do not offer load-time symbol resolution. On
such platforms, run-time portability is a stricter requirement than
link-time portability, and will typically include the precise
placement of the various GSS-API routines within library entrypoint
vectors.
Individual platforms will impose their own rules that must be
followed to achieve link-time (and run-time, if different)
portability. In order to ensure either form of binary portability,
an ABI specification must be written for GSS-API implementations on
that platform. However, it is recognized that there are some issues
that are likely to be common to all such ABI specifications. This
appendix is intended to be a repository for such common issues, and
contains some suggestions that individual ABI specifications may
choose to reference. Since machine architectures vary greatly, it may
not be possible or desirable to follow these suggestions on all
platforms.
B.1. Pointers
While ANSI-C provides a single pointer type for each declared type,
plus a single (void *) type, some platforms (notably those using
segmented memory architectures) augment this with various modified
pointer types (e.g. far pointers, near pointers). These language
bindings assume ANSI-C, and thus do not address such non-standard
implementations. GSS-API implementations for such platforms must
choose an appropriate memory model, and should use it consistently
throughout. For example, if a memory model is chosen that requires
the use of far pointers when passing routine parameters, then far
pointers should also be used within the structures defined by GSS-
API.
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B.2. Internal structure alignment
GSS-API defines several data-structures containing differently-sized
fields. An ABI specification should include a detailed description
of how the fields of such structures are aligned, and if there is any
internal padding in these data structures. The use of compiler
defaults for the platform is recommended.
B.3. Handle types
The C bindings specify that the gss_cred_id_t and gss_ctx_id_t types
should be implemented as either pointer or arithmetic types, and that
if pointer types are used, care should be taken to ensure that two
handles may be compared with the == operator. Note that ANSI-C does
not guarantee that two pointer values may be compared with the ==
operator unless either the two pointers point to members of a single
array, or at least one of the pointers contains a NULL value.
For binary portability, additional constraints are required. The
following is an attempt at defining platform-independent constraints.
The size of the handle type must be the same as sizeof(void *), using
the appropriate memory model.
The == operator for the chosen type must be a simple bit-wise
comparison. That is, for two in-memory handle objects h1 and h2, the
boolean value of the expression
(h1 == h2)
should always be the same as the boolean value of the expression
(memcmp(&h1, &h2, sizeof(h1)) == 0)
The actual use of the type (void *) for handle types is discouraged,
not for binary portability reasons, but since it effectively disables
much of the compile-time type-checking that the compiler can
otherwise perform, and is therefore not "programmer-friendly". If a
pointer implementation is desired, and if the platform's
implementation of pointers permits, the handles should be implemented
as pointers to distinct implementation-defined types.
B.4. The gss_name_t type
The gss_name_t type, representing the internal name object, should be
implemented as a pointer type. The use of the (void *) type is
discouraged as it does not allow the compiler to perform strong
type-checking. However, the pointer type chosen should be of the
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RFC 2744 GSS-API V2: C-bindings January 2000
same size as the (void *) type. Provided this rule is obeyed, ABI
specifications need not further constrain the implementation of
gss_name_t objects.
B.5. The int and size_t types
Some platforms may support differently sized implementations of the
"int" and "size_t" types, perhaps chosen through compiler switches,
and perhaps dependent on memory model. An ABI specification for such
a platform should include required implementations for these types.
It is recommended that the default implementation (for the chosen
memory model, if appropriate) is chosen.
B.6. Procedure-calling conventions
Some platforms support a variety of different binary conventions for
calling procedures. Such conventions cover things like the format of
the stack frame, the order in which the routine parameters are pushed
onto the stack, whether or not a parameter count is pushed onto the
stack, whether some argument(s) or return values are to be passed in
registers, and whether the called routine or the caller is
responsible for removing the stack frame on return. For such
platforms, an ABI specification should specify which calling
convention is to be used for GSS-API implementations.
References
[GSSAPI] Linn, J., "Generic Security Service Application Program
Interface Version 2, Update 1", RFC 2743, January 2000.
[XOM] OSI Object Management API Specification, Version 2.0 t",
X.400 API Association & X/Open Company Limited, August
24, 1990 Specification of datatypes and routines for
manipulating information objects.
Author's Address
John Wray
Iris Associates
5 Technology Park Drive,
Westford, MA 01886
USA
Phone: +1-978-392-6689
EMail: John_Wray@Iris.com
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RFC 2744 GSS-API V2: C-bindings January 2000
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